The WHOis details for the domain name has it owned by Microsoft as of June 14th 2010. Right now 343 Industries is busy on a "new high profile Halo".
Last month a trademark for Gears of War: Exile was found and it's believed to be a very special Kinect-enabled title in the series. Meanwhile Microsoft Game Studios' internal Halo outfit, 343 Industries, is crunching pixels on a brand new Halo title.
There is also speculation that 343 is polishing Xbox original shooter Halo: Combat Evolved into a full HD re-release for Xbox 360. Halo and Kinect... inevitable right?