I think you should add to Windows Mobile version support for modaco's AppToDate.
It gives you ability to make updating of your app very easy.
Here you have links to posts on modaco about how to add support for AppToDate.
http://www.modaco.com/content/apptodate/267098/developers-how-to-include-apptodate-support-basic/
http://www.modaco.com/content/apptodate/267789/developers-how-to-include-apptodate-support-advanced/