Cameyo does application virtualization and has a web service you can consume in your own .Net projects. More info on the web service can be found here.
You can find a read-only svn checkout of the SDK source code (written in C#) at http://code.google.com/p/cameyo/source/checkout
EDIT: the svn URL is http://cameyo.googlecode.com/svn/trunk/