UPDATE: No. Most of Halo 3's features are known at this point. Bots are not in the game.

This always gets asked. Bungie hasn't ever done a multiplayer game with bots. It's conceivable, I suppose, but not at all likely.

UPDATE: The below was written in early 2007. Approximately two months before release, Bungie announced that Halo 3 will feature cooperative play via split screen (two players per box) as well as system link and Xbox Live (four players per game). In a four-player game, the host players the Master Chief, and the other players are the Arbiter and two other Elite warriors.

Any combination can be used; four players can use separate consoles over XBL or system link; two players can share a box and connect to players on one or two other separate boxes.

UPDATE: The below was written in early 2007. Approximately two months before release, Bungie announced that Halo 3 will feature cooperative play via split screen (two players per box) as well as system link and Xbox Live (four players per game). In a four-player game, the host players the Master Chief, and the other players are the Arbiter and two other Elite warriors.

UPDATE: The below was written early in 2007. By mid-summer 2007, most of Halo 3's feature list was known; to date there is no mention of other Spartans, and the four-player cooperative feature uses the Chief, the Arbiter, and two Elite warriors as characters.

This is a perennial favorite question ever since the Halo backstory in Fall of Reach revealed that other Spartans did, in fact, survive.

Bungie so far has not announced anything specific regards to plot or gameplay features.

UPDATE: The below was written early in 2007. In mid-2007, Bungie announced the official release date of Halo 3 as September 25, 2007 for the Americas.

All Bungie has said so far is "2007". Speculation is already beginning that this is a conservative estimate and that Halo 3 will ship this winter. This is most likely naught but wishful thinking.