When Jun Takeuchi surprised Tokyo Game Show attendees with a motion-controlled version of Resident Evil 5
(subtitled "Alternative Edition"), he also revealed some new included content, reportedly
a flashback scene set in the Spencer Mansion featuring Jill Valentine
According to an IGN translation of a Dengeki Online article, the new scene (and whatever else Alternative Edition
includes) may not be constrained to Sony's platform. Dengeki says that the new content may come to 360, but in a "different format," possibly implying a DLC release on Xbox Live Marketplace.
It's great news, but keep in mind: there will only be motion control–support on one platform.