First of all, we've resisted the temptation to do, "Halo for Xbox 360 launch", so how about some biscuits? Second, according to numerous reports based on Microsoft's recent show-and-tell tour of the American tech-and-games-press circuit, Xbox 360 will launch with legacy support for Xbox titles Halo and Halo 2.
Microsoft's Peter Moore said at X05 that some Xbox 1 games would be backwards-compatible at the launch of 360, and said, "We will probably be in a position in about two weeks to give you a list," which means we can probably expect one either this week or at least soon.
That Halo and Halo 2 are on the list is about as surprising as another viral marketing campaign, but there you go. We'll let you know when the rest of the list's confirmed.