TeamXbox has a feature on the Xbox 360's probable launch lineup; the games that will make it, those that won't but should, the ones you might not know about, and a category called "where the hell is" games. The article begins by mentioning Halo:

Halo. Perhaps the most important launch title of all time. You could easily argue that there have been better console launch titles, but it's hard to discount how important Halo has been to the success of the Xbox. Face it - launch titles can make or break a console. Launch titles also set the tone for the system, giving gamers a pretty good glimpse at what to expect in the future. Put a bad taste in a gamer's mouth with a paltry, unimpressive launch lineup, and hear them all mutter "Dreamcast 2" under their breath.

However, strangely enough, Halo 3 is mentioned on only two the six authors' lists. Nate puts Halo 3 down under "won't make launch but should have":

Despite the fact that the words "launch" and "Halo 3" have never been in the same sentence with one another doesn't change the fact that playing the Xbox 360 on launch day with no sign of the series that made the original big black box what it is today just doesn't feel right.

Matt puts Halo 3 on his "where the hell is" list:

So my question is where the hell is Halo 3? At this point, nothing has been said aside from rumblings on message boards, and whispers of secret room meetings. So will we see Halo 3 on the 360? I don't doubt it, it's too much of a flagship series, but c'mon, lets start seeing some details already.

(That sums up my opinion as well: Gates' bravado over releasing Halo 3 in time to spoil the PlayStation 3's launch sounds like a great idea, but it's a poor substitute for having the Master Chief riding shotgun for the new console himself on launch day--Ed.)