Saw this on Diaspora the other day: http://www.freegamealliance.com/index.html
Not sure how frequently they change the games being displayed, but it's a very nice initiative. Wish there was more reliable sources of libre-game news.
For the sake of sharing, those are the other sources I frequently go when I'm searching for libre-games:
Game development! Discussions about game development and related fields, and/or by game developers and related professions.