The Windows Web Services API (WWSAPI) is a new "minimalist" web services endpoint library available on Windows. It's currently in beta along with Windows Server 2008 R2 but includes support for down-level platforms including Windows Server 2003/2008, and XP/Vista/Windows 7 (from the client perspective).
We've developed a demostration project for WWSAPI which is now posted here. This is accompanied by a walk-thru by the WWSAPI development team here.
Learn more about WWSAPI at the MSDN Online Library.