IGN.com have posted some news on the forthcoming XBox 360 Version of UT3. Besides the snazzy new trailer which is below, there's still no word on if user-created content is available or not, but it does reveal that the 360 version will get some exclusives:
The Xbox 360 release will contain five new exclusive maps those other platforms didn't get, two new characters and will include two player splitscreen action. All that and it also sports all of the downloadable content that Epic has created for the PS3 and PC.