This could be interesting. Businessweek:

Armed with licenses from the music labels and publishers, Apple will be able to scan customers’ digital music libraries in iTunes and quickly mirror their collections on its own servers, say three people briefed on the talks. If the sound quality of a particular song on a user’s hard drive isn’t good enough, Apple will be able to replace it with a higher-quality version. Users of the service will then be able to stream, whenever they want, their songs and albums directly to PCs, iPhones, iPads, and perhaps one day even cars.

Sounds good, but of course price is going to be the key factor. The article suggests that it might be rolled into MobileMe, the£60-per-year cloud sync service Apple currently offers. That makes sense: MobileMe’s been due a revamp for a long time, and the rumours have been suggesting a music angle for a few months now.