The SciFi Channel in the U.S. has always shown Battlestar Galactica on Friday nights, at 9pm or 10pm EST. When they stupidly and separated it from its two Stargate lead-ins as a precursor of canceling Stargate SG-1, the ratings began to drop a little for Galactica (although honestly they're still doing fine for first-run cable, as SG-1 had been doing when they canceled it). Now the rumor is that the programmers at SciFi want to move it into a competitive timeslot opposite one of the most popular and best new shows on network TV, Jericho. Michael Ausiello at TVGuide for some reason thinks it "could go a long way in boosting the show's ailing Nielsen's".
I would expect it to do the reverse. SciFi's viewership has long reserved their Friday evenings for these three shows (now with Doctor Who added), and separating the original trio hurt the ratings for both shows. Still, all of them have remained on Fridays, just at different times of the year. Moving one of the shows to another night when people already have something to watch is just going to make it worse. Unless they manage to have it showing on Wednesday only during the mid-season hiatus for Jericho, I just can't see this working to increase the ratings. Even though one show is on the surface supposed to look like science fiction, and the other is set on earth in the near future, there really is a huge similar between the two post-apocalyptic survival-of-humanity stories, with the focus on the things people do in desperate situations and the character development amidst the events usually overshadowing the events themselves. I imagine the same kinds of people are drawn to both shows.
Update: It's going to be Sunday nights at 10pm. That's much, much better.