As you might have read, we just introduced Exchange 2010 SP2 RU4 for public consumption. You can find a list of the things fixed located at the URL listed prior, and review the associated KB articles.
Once thing that did come up was that retention policies did not properly tag the calendar or notes, which was a problem for most users. With that said we have resolved this issue for Calendar and Tasks retention tag supportabilty as discussed by Ross Smith IV (Principle Program Manager for the Exchange Customer Experience Group) here.
Any questions, as always feel free to list below.