Windows Live ID Client 1.0 SDK!
The Windows Live™ ID Client 1.0 software development kit (SDK) provides a managed API for Windows Live sign-in from within desktop client applications. Included in the release is a sample application together with its source code so that you can build your own client applications.
For more information, please check out below link
http://www.microsoft.com/downloads/details.aspx?familyid=B5A78784-922D-4267-A6E9-5D2ECF1DCED8&displaylang=en
HC