http://www.youtube.com/watch?v=P7OQRA2k ... r_embedded
Seem to have release quite a bit of their core java libs as open-source:
http://www.threerings.net/code/
Especially their game gardens ( http://www.gamegardens.com/) network lib seems to be really interesting at a quick glance (edit... ok it is somehow used to run games on their servers... but never the less it could be interesting for some projects with commercial aspirations).
Seems like Java games (especially given their easy portability to Linus and Android) have a bright future... and with things like Motorola's mobile phone desktop replacement/hookin and the current craze of tablets... Android compatible FOSS games could become mainstream quicker than you think
I guess it is time to look at things like http://jmonkeyengine.com/ again if you are starting a new FOSS game project
