On the MSMQ front, only two hotfixes are listed:
from a total of 625 documented for the service pack.
There may, of course, be undocumented changes where an update was not previously released separately and so has no associated KB article published.
According to the Core Team,
- Volume Licensed, MSDN and TechNet subscribers get access February 16th, 2011.
- All customers get access February 22nd, 2011, through Windows Update and direct download
So get ready to start testing.