Apple posted an announcement on its developer boards on Sunday, warning existing users of the beta builds of iOS 5 and Mac OS X that the backup data on iCloud will be removed from its servers on September 22, according to a report by 9to5Mac:

On Thursday, September 22, the iCloud Backup data will be reset. Backing up to iCloud or restoring from an iCloud backup will be unavailable from 9 AM PDT – 5 PM PDT. If you attempt a backup or restore during this time, you will receive an alert that the backup or restore was not successful. After this reset, you will be unable to restore from any backup created prior to September 22. A full backup will happen automatically the next time your device backs up to iCloud.

iOS and Mac OS X developers have been testing the cloud-based service since June this year and are currently on its tenth beta. The company has stated that iOS 5, along with iCloud, will be launched in the fall, and it looks like we’ll be able to lay our hands on the OS before the end of this month.