I really should mention Icculus. Following this link navigates you to one of the few guys, dedicating their enthusiasm to linux game development. Actually Icculus is an open source hoster for game development (as far as I can see, 'cause it's hard to find more information on the site), but the hoster Ryan, once Loki developer, has essentially done some important Linux ports, including Unreal Tournament 2004, America's Army, Descent 3, and Serious Sam.
Of course there exit other some other open source hosting sites, but Icculus is striclty for games. Anyway, some alternatives