so it turns out (sorry been in seattle too long where every sentence starts with "so") the availability mp has some issues. hence it's been pulled from the microsoft website. if you have the exchange mp installed, do not install the availability mp (yet). It's going to be updated soon, though... keep your eyes open.
anyway, the current version pulls out the following groups:
Microsoft Exchange Server 2000 Backend
Microsoft Exchange Server 2003 Backend
it replaces it with the following groups:
Microsoft Exchange Server 2000
Microsoft Exchange Server 2003
the only workaround right now is to re-import the exchange mp. fun.