Those who have already gotten themselves up on iCloud are going to have to hold on for a minute.
On September 22nd iCloud is going to reset its backups for all users, and they will be unavailable for the business hours of that day. This will render all the backups that were made before this date useless, and you will have to re-establish your backup files.
The Blog 9 To 5 Mac recently reported this development and that beginning at nine in the morning PST that the system would go down until five that afternoon. For those that do try they will be told that the backup was unsuccessful, as well as anyone trying to restore their device. This problem is exclusive to developers who have been testing the iOS 5 before its official release date later this fall.
The developers have had the iCloud services available to them in seven various beta versions so that they can begin to try to integrate these features into app updates and new software, and this could be the ramp up to the fabled Golden Master version of the software that will be the final in the string of updates. Most iOS 5 rumor blogs have been stating that this Golden Master would be released on September 23rd, and this latest news seems to lend it some extra credibility. This does come, however, in the wake of a failed rumor promising the eighth beta version a few days ago, which never arrived.
Issues like these are to be expected when running unfinished beta versions of the iOS 5, which really will not have the stability of services until the final version is released.