I've been reading through the BlackBerry Enterprise Server for Microsoft Exchange Version: 5.0 Performance Benchmarking Guide and picked up a few read-worthy things.

A somewhat English translation of how IT Policy works (in RIM's words)

Sending IT policy updates to BlackBerry devices

If you assign an IT policy to a user account or group, change an existing IT policy, or delete an existing IT policy, the BlackBerry® Policy Service sends an IT policy update...