Technical Hurdles for Win32 rsync port

The way that windows locks open files might cause an issue requiring you to hook into the Volume Shadowcopy Service.

About two years ago this fellow ported the algorithm to C#. I haven't taken a look at the code (or the provided binary), but it might be a place to start looking or someone to try contacting.
http://www.russiantequila.com/wordpress/?p=8