Hey! I have just fixed the problem! Here is want you need to do:
1) Pick up the iOS 5 device
2) Close Mail.app and get rid off it in Multitasking bar, too
3) Go to "Settings.app -> iCloud"
4) Delete the account (don't worry, everything will sync back from iCloud later)
5) Close Settings.app and get rid off it in Multitasking bar, too
6) Turn off and on the device (TURN OFF and NOT hard reseting it by pressing and holding "Power + Home")
7) Go to "Settings.app -> iCloud" and type in your iCloud account.
That's it! I worked for me. Hope this will help!
I've removed my account. reset my password and added my account again.
That help me to get into my email account on my iphone. But I still have problems.
I can not move mails to the trash since I dont have a trash dir in the icloud acct on my iphone.
Also I can not log into my email with Mail on 10.6.8 with this account, what ever imap/smtp servers I use.
And I get Wrong password when I try to login on iChat with the account.
Anyone with the same ichat problem as well?