“SCCM” is not the official acronym for Systems Center Configuration Manager 2007. "ConfigMgr" is. “SCCM” is not owned as a trademark by Microsoft and therefore we really cannot use it. But I have noticed that many people have picked up on it and continue to use it. Even me, for instance: my main blog site is named SCCMNAP.Com.
I added the acronyms for each of the Microsoft System Center Products I found here.