Living with Windows Mobile 5 and Direct Push email
Geekzone: Living with Windows Mobile AKU2, or How I learned to Love Push e-mail and Stop Worrying
A. Karantze shares some of his experiences using a Windows Mobile 5 device that has the Messaging & Security Feature Pack (MSFP) installed.
The article talks about how Windows Mobile updates are made available to users and by whom. AKU2 refers to the Adaptation Kit Update that Microsoft makes available to device manufacturers and carriers. This is the software update that they can choose to make available to customers.
It's a good read if you're interested in learning more about Microsoft's mobile messaging system built right into Exchange Server. He also comments on data usage with Exchange ActiveSync.