There was a yellow alert on .Mac syncing for Friday. I didn't check the status today, but Apple was acknowledging some issues yesterday, due to "scheduled maintenance."
FWIW, Sync threw a bunch of error messages and conflict screens up during my first Leopard sync. A lot of the conflict screens were about stuff from 2004 and 2005. Um, okay.
After those first couple of syncs, things have been fine.