"Microsoft has informed me that those updates will start appearing on Microsoft Update in mid-December. I’m also told that the Exchange team will be writing about this shortly on their blog and that a Webcast on this subject is scheduled on January 17th."
So keep your eyes on the blog. These are just IMF definition updates but the faster you get the definitions the more spam you can kill. If you want it realtime, you know what will defend your Exchange the best. 😉