This is the big story in tech today as everyone gathers to watch Apple unveil its latest thingy at noon central, 10 pacific. We know it will involve something called iCloud, which will likely offer the ability to store music in the cloud and buy new music and stick that up there in the cloud as well. How exactly that will work, what it will cost, how much storage you get, can't say just yet. Apple is also expected to launch Lion, the new operating system for Mac, and iOS 5, the new operating system for mobile devices.
Unlike previous years, there doesn't appear to be some big shocking device announcement (last year it was the iPhone 4). I suppose it's technically possible that such an announcement will happen but it would mean a better job at keeping secrets than even Apple has ever done before.