A few numbers after the keynote would be fine. Putting an album, anyones album preloaded on a new iPhone will quickly become the sole point of consideration.
Many of Apple's product launches have been promoted on the basis of a single key benefit; Tiger, Spotlight. Leopard, Time Machine, iPhone 3G - 3G. iPhone 4, retina display.
Including anyones album, especially a group as self aggrandising as U2, would become the main point being quoted in press coverage, tech reviews etc over and above whatever they key benefit(s) of the new hardware might bring.
Hopefully this will prove to be idle speculation, if for no other reason of Bono loudly proclaiming that he couldn't have access to Apple's tech labs and that Blackberry were U2s partners in bringing their vision/music/whatever to the world.