this is pretty good write up.
This document was created to evaluate the various experiences that an Information Worker (IW) can have based on Exchange ActiveSync Policies being applied onto their devices in different states.
First Time Policy Applied onto device
Modify specific settings on device within the same policy
Reassign user to a new Exchange ActiveSync policy
Removing an Exchange ActiveSync policy from the user
The Exchange 2007 Wiki - IT Policies: "Exchange ActiveSync Policy User Experience"