Peter Kirk takes Obama's conversion experience as evangelical (but see his comment below resisting the seemingly-uncontroversial inference from having an evangelical conversion experience to being an evangelical). The interview Peter links to in support actually leads me to conclude that he's definitely not an evangelical, and a case can even be made that there's nothing distinctively Christian in his personal faith. Let me first outline what I think the boundaries of evangelicalism can include, and then I'll look at some of the things Obama says that make me think he's outside the realm of evangelicalism and perhaps even not very specifically Christian. Much of the content here is adapted from comments in my conversation with Peter in the comments.
Theologically liberal views (at least compared to the status quo in evangelicalism) would include people who reject the substitutionary element of the atonement but retain a penal element (e.g. my co-blogger Wink), who support open theism but insist that God has a plan and will win in the end (e.g. philosophers Dean Zimmerman and Dale Tuggy), who are universalists of the sort that they're convinced everyone who goes to hell will eventually repent and follow Christ once they see the consequences of not doing so, and thus evangelism is still urgent, and hell is still real but just not eternally populated (e.g. Keith DeRose), who are inclusivists of the sort where Christ's sacrifice in fact atones for some in other religions because general revelation teaches them that God must provide a solution to the sin problem and trust him to do so (e.g. the C.S. Lewis view), that a homosexual lifestyle is morally ok but who feel the need to reinterpret scripture to defend such a view (e.g. I have a friend who holds such a view and is clearly an evangelical) rather than saying the Bible includes an immoral prohibition.
There are some who deny inerrancy (but really affirm it and just deny a straw man that they think inerrancy is), but I think actual denial of inerrancy is harder to maintain while being an evangelical. The Fuller Theological Seminary model makes an effort by still insisting that scripture is infallible on any moral teaching or theology within its pages. (Some at Fuller don't actually follow this. I know of one who thinks Paul was a complementarian but insists that we shouldn't be, and I think that moves out of the range of evangelicalism.) But I think you can say that there are errors in dates and place names in the Bible and still count as being within evangelicalism, just on the fringes. Once you start explicitly questioning the plain moral and theological teaching of scripture without trying to reinterpret it so that you at least believe scripture teaches your view, it's hard for me to see that as even on the fringes of evangelicalism. That's just theological liberalism in its most plain form.
So I'm certainly open to finding liberalizing tendencies within evangelicalism, even if one is on the fringes for holding certain views. Some of these are closer to the fringes than others (e.g. Wink's view of the atonement doesn't seem very extreme to me, just extreme-sounding to those unwilling to think very hard about what they've been taught). Those who combine several of these are more on the fringes than others. But one can be an evangelical and hold such views. It's a separate matter whether someone is a Christian but not an evangelical. I'm not saying here that one must be an evangelical to be a Christian. I know plenty of people whom I would not consider evangelicals but who do lay claim to being more broadly Christian. Very few Catholics are evangelicals, in my view, although I personally know a handful who I think are evangelical Catholics. I do think pious Catholics are Christian in a perfectly normal English usage of that term. I know a number of people who I think are Christians in mainline denominations who aren't evangelicals by the criteria I've outlined above. Some evangelicals want to restrict the term 'Christian' so that it only applies to evangelicals, but it's linguistically inappropriate to do that given what the term has come to mean.
But suppose someone denies the reality of hell and then expresses skepticism even about the existence of an afterlife in heaven. What if you say you pray, but then when you go on to explain what you do when praying it becomes clear that you're just maintaining an internal dialogue evaluating your life? What if you talk about a power that goes out of you when you speak the truth (rather than inflating your ego or playing rhetorical games), and then when your interviewer asks you if that's the Holy Spirit, you prefer to speak instead of just seeing a common recognition of truth outside of you? What if you're willing to talk of Jesus as your personal means of bridging the human-God gap but think of that in terms of reaching something higher rather than as the solution to a problem of sin? Speaking of sin, what if you admit to believing that there is such a thing but then define it entirely in terms of going against your own convictions, as if hypocrisy is the only sin? In the above-linked interview, Barack Obama did all these things.
(I should also note that he clearly expresses a theology of works-earned salvation, even in the limited kind of salvation that he admits to in this life. That alone is going to make it hard to place him in the evangelical camp, given that he's basically denying the very Reformation that evangelicalism insists is central to Protestantism, and evangelicalism is unquestionably a Protestant movement, even if a few Catholics who in practice resist Catholic teaching on that issue can count as evangelicals.)
It's hard for me to see someone who says all that as even distinctively Christian, never mind an evangelical. Sure, he attended a culturally-Christian church rooted in traditions the historically black church in America had developed. But a closer examination of Wright's theology showed that he rejected the crucial Christian conviction that all who are Christians are united in Christ, choosing to reject white Christians as his brothers and sisters, and he at least toys with the rejection of the gospel itself in favor of a social gospel. So I don't think Obama's church affiliation counts as being very strongly in favor of his being an evangelical.
I'm pretty open to thinking of someone as evangelical, albeit on the fringes, even if one is not theologically conservative. I consider Keith DeRose an evangelical because of the way he frames his universalism in a way that fits it to core evangelical convictions. There are some whose views I simply can't discern, such as Brian McLaren, largely because he never really comes down on the details of the views he makes a lot of hay about questioning. But some have expressed enough of a clear rejection of core evangelical convictions that I think there's reason not to consider them evangelicals, and in some cases I'm not sure there's even anything distinctively Christian about their religious views, even if they attend a Christian (in name at least) congregation.
This seems true of Obama from this interview. I expect it's probably true of J.K. Rowling, for the record (and I'm a big fan of her work). If I had a chance to sit down with either and talk about their faith, I'd try to steer the conversation in a way that might help provoke them toward genuine faith and commitment. If it's an issue of their own ultimate salvation, I would certainly try to seek their own good. But it seems to me that Obama could just as easily have had pretty much the same faith he has if he had instead found himself in Mormonism, Islam, or Unitarian Universalism, and the only reason he was in Wright's church was its political usefulness and his personal friendship with and admiration for Wright in the political context he'd known him in (regardless of what he said about Wright later on when it was more convenient to ditch Wright). It thus makes it very hard for me even to be sure there's anything distinctively Christian about his faith, and he seems to be pretty solidly outside the range of views that I can comfortably see as even on the fringes of evangelicalism.
I'd happily support someone for president who I think would be the better president, even if I didn't consider that person an evangelical or a Christian at all. My judgments on this question have nothing to do with politics. I'm certainly not sure that John McCain is an evangelical either, for the record, and I even have some hesitations about George W. Bush (although there's at least a prima facie reason in his case, and I haven't seen real evidence to the contrary). This isn't about politics. I just don't think Barack Obama's views are within the realm of evangelicalism, and I'm not even sure there's anything about them that makes them genuinely Christian as opposed to just loosely Christian-like enough to fit into a theologically liberal, loosely-Christian denomination like the UCC and its particular black-liberation-theology incarnation at Trinity in Chicago.