Sandcastle produces accurate, MSDN style, comprehensive documentation by reflecting over the source assemblies and optionally integrating XML Documentation Comments.
Via Sandcastle Team Blog:
I am excited to announce the availability of October 2007 CTP version for Sandcastle. The latest version is now available for download at http://www.microsoft.com/downloads/details.aspx?FamilyId=E82EA71D-DA89-42EE-A715-696E3A4873B2&displaylang=en.