I have updated ipad2 to ios5 etc and my me.com email is setup (and migrated) but the icloud tab in settings is greyed out (so is twitter).
I cant access any of the icloud settings on the ipad2 but it all works on my iphone (3Gs).
Thanks Feldur in another discussion....
I had completly forgotten about my restrictions being turned on. You saved my night.
Went into General > Restrictions > And allowed changes to accounts!!
All greyed out options now available - Worked like a charm