http://openxcom.org/
It does work and it is very cool. If you have the original you will want to check out this project.
Played a bit last night and the new options, AI, and resolution options make for a good time.
Signing up to keep track on that.
Bumping to provide a bit more info:
1.) The game does require a paid version of X-Com (the original, either American or British version). Steam suffices but bought from anywhere would be fine. The original game must be installed validly on a computer. The OpenXcom installer then asks you to point to the proper folder and it imports the game files to a new OX folder which then installs patches and upgrades. (I could also install OX without the patching project, although I'm unsure what the point would be to that.)
2.) A nice selection of options, including 1080p support and a metric ton of openGL rendering protocols. I honestly don't have a single clue which one I should be using, so I just used the one actually labeled OpenXcom. :)