No More Halo 3 From Bungie

In an interview with IGN, Brian Jarrard said that Halo 3: ODST will be the final peice of the Halo 3 pie;

"Overall though, we are viewing the ODST campaign and the included multiplayer maps as the final exclamation point in our ongoing efforts to extend the Halo 3 experience."

After Halo 3: ODST Bungie will continue to work on their, as of yet, unannounced project.