They're not calling it that, but the original series of Star Trek is getting a treatment something like what George Lucas did with episodes 4-6 of Star Wars when he called it the Special Edition. There won't be any deleted scenes added in or anything like that, but it will have new CG effects, stuff added in into the backgrounds, better space scenes, decent planet landscapes, more people milling around in the background in scenes on ships and starbases, and so on. They won't be doing these in order but will instead start with fan favorites. "The Balance of Terror" will be first. That episode introduced the Romulans (and maybe will have decent-looking ships for them now). The only other episode mentioned was "Miri", in which the crew encounteres a planet full of children who age rapidly and die once they reach a certain age.
We already have some sense of what this will look like, including what the ships will be like and what some aliens will look like, since they already did some of this when the DS9 crew visited the TOS Enterprise during the Tribbles episode and then again on Enterprise when the mirror universe Enterprise crew encountered the main Trek universe TOS-era Defiant. We've seen CG versions of that era's ships. The Tholians and the Gorn looked great on Enterprise, and I hope they can do the same thing for other aliens. I wonder if the new Andorian look on Enterprise will lead to some CG changes for these remasters, but it will be hard to do much given that they probably won't recast and reshoot the scenes with new actors. Since they've now fully explained the change in Klingon look, they probably don't need to do any touchups there, but the Klingon ships are in the same category of the Romulan ones, needing a major overhaul to look at all decent.