Here's my situation: I have the new iPhone 4S which is using iCloud beautifully. However, my MacBook is still using MobileMe. When I go into System Prefs > iCloud, it has a big button that says "Click here to move your MobileMe account to iCloud."
When I click that button, the browser goes to me.com/move, then I log in, and it immediately redirects to me.com/find and then a screen appears saying "Ok, you're all set, you may now start using iCloud."
Except… I'm not. When I go back to the System Preferences > iCloud, it still has the "you need to move from MobileMe" screen and the button to start the transition. And I am 99% sure that my contacts, calendar etc are not syncing with iCloud, so I can't get them on the phone (that's a problem).
So… the phone is all set on iCloud, but I need to tell Lion to use it. I assume the me.com/move web page someone would send a message back to Lion saying "ok, this user has made the transition, now you can show the 'real' iCloud preferences panel," but that hasn't happened.
HELP!
Best Answer
I found the answer: log out of MobileMe in the System Prefs panel, and then the iCloud panel will prompt you to log in (instead of offering the "Move to iCloud" button). Log in with your iCloud account and you should be all set. Worked perfectly for me.