In an interview with GamePro, Bungie's own Joe Staten talks about Halo 3: ODST, due out this fall, clarifying when the game takes place (between the end of Metropolis in Halo 2 and the Arrival scene that begins Halo 3).

Of course, he also teases fans about an unknown enemy, but what do you expect? It's Bungie.

Saw the link in 2900d4u's post in the HBO forum.