T-Mobile USA released an official ROM upgrade for the MDA that includes the Messaging and Security Feature Pack (MSFP) for Windows Mobile 5.

One of the coolest features included in MSFP is Direct Push, which keeps your Inbox, Contacts, Calendar and Tasks always in-sync with the data on your Exchange 2003 SP2 server. What that means is that if you send me an email right now, it should appear on my cellphone within the next 10 seconds, no matter where I am, as long as I have a cell signal.

I installed the new ROM over the weekend - a completely painless, five minute task. I didn't need to backup anything even though the device was going to get erased because all of my data, including my phonebook, sits on the Exchange server and is one sync away. It's just such an incredibly seamless experience.