SEM = Paid, SEO, SMM?

No wonder our prospects are so confused – EVERYONE – has a different term / meaning for SEM and Paid Search advertising.  To me, SEM = Paid Search (mostly because it works in tandem well with SEO – and the Paid / Organic dichotomy there).  Apparently other, LARGE entities consider it to be so much more… or do they even understand what they’re talking about?  (Thanks, Search Engine Watch & Rebecca Murtagh)