Smitty2k1, the summary is;
MB Server - A new app to manage your media pool centrally. This can be installed on a dedicated media server (Win7/8/WHS)
MB Classic - Essentially the 'old' media browser app (still within the confines of WMC) that has been tweaked to use MB Server for all media. This does allow you to distribute thin MB Classic clients easily.
MB Theater - The first standalone (non-WMC) feature rich app bearing the MB name. Very slick interface, can still use MB Server, and now uses VLC as the standard player. I think this is where most of the 'front end' development will go.