"PDAs, and especially smartphones, are very popular devices. Sadly many IT departments still ignore Windows Mobile devices. The devices live in the grey area where they do interact with the business systems (like Exchange and Sharepoint), but are not secured according to company policy. This results in an unmanaged risk in the infrastructure: the devices do contain business information but no demands are posed upon them to make them secure. We identify the risks that are introduced and show you that these risks are in fact unnecessary because you can do reduce the risks without adding costs or overhead. In this article we show how you can achieve a reasonable level of security that has minimal impact on user experience and budget."
If you're looking to consider WM devices in a business environment, and the security implications thereof, you'll want to take a look at this article by Jaap van Ekris.