So what is the iCloud? First of all, is it "the iCloud" or just "iCloud"? Who knows? From what I can surmise it is basically going a place to keep all your itunes song, books. Will the app store be there? I don't know.
I found this great article from PC World that can break down what they think "the iCloud" will be here it is:
Link to: PC World iCloud article