At our Mobile and Embedded Developer Conference I presented a session on the Top 10 Security Concerns that I typically see for customers looking to deploy Windows Mobile.  Rather than just highlighting these I also shared some solutions and approaches to each of these concerns. 

I've just uploaded my presentation to SlideShare where you can view it and also download it!

http://www.slideshare.net/jasonlan/top-10-security-concerns-of-windows-mobile-and-how-to-overcome-them  

 Hope you find it useful!