The following support document states that you get 5GB of free iCloud storage of messages in the form of iMessages, SMS and MMS. http://support.apple.com/kb/HT

The following support document states that you get 5GB of free iCloud storage of messages in the form of iMessages, SMS and MMS. http://support.apple.com/kb/HT4859?viewlocale=en_US&locale=en_US http://support.apple.com/kb/HT4859?viewlocale=en_US&locale=e... It doesn't state how the iCloud backup is stored however.