Are iMessages stored anywhere other than directly on your phone?

Simple question....but there seems to be no simple answer out there.

A standard text message is stored on your phone and your phone alone (minus the carrier's records of course).

What's not clear is if your iMessages are saved, backed up, or simply put some where other than your phone where others could get access to? With the icloud and new syncing features I just want to make sure these messages do not automatically become some part of iCloud or some other system.