I've read about them though I've never tried them. Both of those projects started about five years ago didn't they? I can't keep track either though there's definitely a few very long running projects out there. The Atari 2600 was my first game system but I find it harder to get into new games on that system than even slightly newer ones. It's just a little bit too limited...
RE: 2600 Chess Homebrew Work in Progress