HTC is really closed when it comes to their API set. Other companies are much more forthcoming. There is no unified sensor SDK in the .NET CF framework. I know what you mean, it would be fun to mess with the proxmity sensor and light sensor. There are some cool apps you could write...hehe. If you ever find anything let us all know.
See:
http://wmpoweruser.com/?p=3355
If I helped, Don't forget to hit Thanks
