I don't have all the details yet but it appears that someone didn't read any of the instructions on doing a MOM 2005 SP1 upgrade at my current client. The management server got updated but the database server did not. We are still getting alerts but heartbeats are failing and we are getting some weird errors. Hopefully upgrading the DB (even though it won't be doing the upgrade in the preferred order) will fix the issues.
I hunted down the following docs on the right way to do it:
http://www.mcse.ms/archive236-2005-9-1792037.html
http://www.microsoft.com/technet/prodtechnol/mom/mom2005/Library/e4114fa0-21cb-4e04-a636-a91499ec8b8f.mspx