With Windows Mobile we now have the ability to manage mobile devices through 3 different solutions:
1) System Center Configuration Manager (SCCM)
2) System Center Mobile Device Manager (MDM)
3) Exchange 2003 and Exchange 2007
There is some confusion as to when you need either SCCM or MDM to manage devices, this really comes down to how much functionality/capability you need in place. If it is purely email access then Exchange may do enough but if you require further capabilities such as VPN, Software distribution or Software Inventory then you may need to consider MDM or SCCM.
The chart below I’ve found to be a great resource to help those discussions/decisions: