Although Microsoft hasn't explicitly said so, it seems fair to infer that Perfect Dark Zero will be one of the Xbox 360's launch titles. We thought it would be anyway, but the matter seems more or less settled following this morning's official confirmation that the game will be on shelves in Europe "this Christmas" - which is as specific as the company's publicly been about the 360's release date.
As in the US, there'll be two different versions; a regular-priced effort, and a two-disc Limited Collector's Edition - presumably for collectors who operate with less than three units of alcohol in their bloodstream.
In that case, disc one is the game, and disc two consists of a behind-the-scenes The Art of Perfect Dark Zero video, as well as a few knickknacks to help spice up your Xbox 360. There's a piece of music from the game called "Limelight" by DJ Kepi & Kat, which ought to do fun things with the 360's built-in visualisations; some pictures you can use on your Xbox Live Gamercard; and a custom skin for the Xbox 360 Guide software.
You'll also find the first chapter of Perfect Dark: Initial Vector - Greg Rucka's novel set six months after the game. Microsoft's commissioned a pair of these novels.
Perfect Dark Zero is one of two Xbox 360 launch titles designed by Rare, the UK developer Microsoft bought a few years ago, and is the next-gen first-person shooter follow-up to Nintendo 64 title Perfect Dark. Rare's other 360 launch title is Kameo: Elements of Power, which is about a girl who can transform into, among other things, a ball of spikes. The real question, of course, is whether she can transform into a decent return on £375 million.