An email sent from Apple to a MobileMe member reveals some details about Apple's upcoming storage allocation in iCloud. When users sign up for a free iCloud account they will receive 5 GB of cloud storage. However, when users near their 5 GB limit they'll receive an email from Apple like the one this MobileMe member received today, as MacRumors reported. The email reveals what happens if you hit your 5 GB limit.
If you max out your data storage your iOS devices will no longer back up or save new data to iCloud