JailbreakMe's jailbreak system breaks the FaceTime and MMS features on many user's devices. Since then, the Dev-Team has worked closely with the creator of Cydia, Jay Freeman aka Saurik, to issue a fix. New JailbreakMe users should simply proceed normally and a new version of the jailbreak will be installed that will not remove FaceTime or MMS from the iPhone.
Users who already installed JailbreakMe get an easy fix as well. They should simply navigate to Cydia and upgrade to the latest software.