So, following up on the problems I had yesterday, I did a bit more research and tried a few things. To make a long story short, I deleted my “birthdays” calendar in iCal and re-synced, and everything was OK. I added the birthday calendar back in, synced again, and things are still OK. The next test, which I’ll probably do tonight, will be to sync Outlook on my PC again, then sync *that* back to MobileMe, and see if the problem returns. Hopefully not.
There’s a heck of a lot of talk on this problem in the MobileMe calendar support forum at Apple. One other thing I did, which didn’t seem to help, was to mess with the time zone settings in MobileMe. I’m back to the Eastern time zone, at least in the account page, but my calendar is showing everything in Mountain time, for some reason. I’m hoping that one will clear itself up.