Rock Band 2 rocking on 360 in Sept. - PS3, PS2, Wii 'later in the year'

While IGN simply reports that Rock Band 2 is "set to ship for Xbox 360 this September and PS3 later in the year," the AP says it will be "available for Sony's PlayStation 3 and PlayStation 2 as well as Nintendo's Wii later in the year." While the two at least agree about the "later in the year" detail, neither answer our biggest question about this arrangement: Is this presumably brief period of Xbox 360-exclusivity a business arrangement – as it was for Rock Band in Europe earlier this year – or simply a development reality?

Sure we've got other questions – like will the PS2 and Wii releases be similar to the watered-down experiences currently available – but with Guitar Hero IV coming out for Xbox 360, PS3, PS2, Wii, and PC in late October, details on the nature of the timed exclusive seem paramount. We've asked the hard-rocking folks at Harmonix to let us in on the nature of the arrangement.