Updated to 2.2 on 9/22. This weekend, I was still getting emails from my exchange server. Looked into my sent items folder for an email. This seemed to disable email delivery to my phone somehow. I was no longer getting email pushed to my phone. After manually trying to retrieve messages, (notification said there were none) tried to see if the settings were blown away. nope.
I deleted the account and re-added it. seemed to resolve the issue
Work runs on Exchange 2003.