Bungie no longer owns Halo but Bungie still has the source code/right to update Halo PC as they see fit. This was even still the case when the 1.09 patch was released being the first piece of software to have Bungie's new legal name signed onto it after they departed from Microsoft. Bungie themselves are going to be hosting the master server, Bungie's lead engineer (Roger Wolfson, AKA Sawnose) wrote the patch on behalf of the community [i]as[/i] a representative of Bungie, and he will be making an official announcement here when the patch is ready for mass release rather than the testing phase that it's in at the current moment.

Bungie isn't updating Halo.

Awesome, although I'm more than curious on how a non sanctioned developer can make an official update for a game he doesn't own.

Bungie don't own Halo.

No, They are not.