As part of the press release announcing the agenda for the WWDC event next week Apple have not only confirmed that cloud based services will play a part in it, but that the name has been confirmed as being iCloud. Over the past few months there has been a lot of speculation about this and even sightings of trademark applications and domain registrations to confirm suspicions. A lot of music labels have reportedly already signed up to the new framework, but I would doubt it will yet cover the full extent of the library available in the iTunes store.
Both Google and Amazon have recently announced cloud based services for storing and listening to music so it would come as not surprise that the long anticipated offering from Apple would be imminent. There are also a lot of rumours flying around that Apple is also trying to sign up for distribution of TV episodes and films using the iCloud service as well. With the big push for digital distribution (which even DC Comics is getting in on the act with) it is starting to seem more likely that we'll see the end of physical media within the coming years.
So between iCloud, OS X Lion, and iOS 5 it sounds like WWDC 2011 is going to be good whether they announce an "iPhone 4S" or not.