Apple has never made the iMessage protocol publicly available for review, but from reverse engineering people have not been able to find evidence of end-to-end encryption, just SSL/TLS to and from Apple's servers.

> I do not see anything about retrieving public keys of users you are sending messages to; hence your message is completely readable/editable by someone at apple's servers.

http://security.stackexchange.com/questions/18908/the-inner-...

Further, an iMessage message can be received simultaneously on all your devices. Unless your private key is synced via Apple's servers, how would end to end decryption work?

And finally, there were incidents some time back where people were receiving messages intended for other people, but were able to read them unencrypted.

It would be nice to get some clarification from Apple on this, along with making the protocol and its security public.