First of all, I have no insider information and this isn’t even speculation on what I think Apple will present at WWDC next week. It is what I would do if I were product manager at Apple considering the various technologies available and what I think would make the most compelling product.
One App for All Devices
We know that Lion and IOS 5 are influencing each other so that apps will be more similar in both environments. Also with the new Mac App store, you only need to buy an app once and it is available on all your Macs. I would go further and make apps (and media, see below) available on all platforms. That is, buy an app once and run it on any apple device: Mac, iPhone, iPod, iPad, Apple TV.
App Continuity When Moving from One Device to Another
Now that you have apps available everywhere, use iCloud to move your environment when you move. So if you are playing a game on your iPhone and get home you can continue the game on your computer or tv. The Kindle does this for books when you move from the Kindle to a smart phone app or any other app that can show the book. Login to any computer with your iCloud account and get the same desktop you left on the previous computer.
App Data Available Anywhere
Of course when you switch from one device to another any documents you are working on have to be available on all the devices. iDisk does this. Dropbox does it better. iCloud should be at least as transparent.
Media is Like Any other Document
Just like you can move a spreadsheet between devices you should also be able to move music, movies, books, etc. the same way. The music locker is what people are talking about but iCloud can be a general place to store all media for use on all devices. Start watching a movie on an Apple tv then pick it up on an iPad.
The Basic Version Should be Free
To get people into the ecosystem the base level should be free. One of the big problems with MobileMe at $100/year is that many people aren’t going to sign up for it. If it is free everyone can use it. Sure, charge to buy or subscribe to music and movies or for large amounts of storage but make the basic locker and the ability for the apps to access data on all the devices a free service.
Capture All Media
I would be willing to bet that Apple won’t do this but if they build radio and tv tuners into appropriate devices then iCloud would be a lot more useful as it would then also be a DVR (plus Slingshot because you could view your media anywhere). In particular this would make Apple tv a much better product. In my opinion.