Microsoft have released a bunch of protocol specifications for their proprietry protocols or implementations. Some of the whoppers I've added to my reading list are (in alphabetical order):

• "FrontPage Server Extensions: Website Management Specification" http://msdn2.microsoft.com/en-us/library/cc217914.aspx
• "Firewall and Advanced Security Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc231461.aspx
• "Local Security Authority (Domain Policy) Remote Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc234225.aspx
• "NT LAN Manager (NTLM) Authentication Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc236621.aspx
• "NTLM Over HTTP Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc237488.aspx
• "Remote Desktop Protocol: Basic Connectivity and Graphics Remoting Specification" http://msdn2.microsoft.com/en-us/library/cc240445.aspx
• "Remote Procedure Call Over HTTP Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc243950.aspx
• "Windows Security Health Agent (WSHA) and Windows Security Health Validator (WSHV) Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc251347.aspx
• "Windows Update Services: Client-Server Protocol Specification" http://msdn2.microsoft.com/en-us/library/cc251937.aspx

The items marked in red are for immediate reading. I am particularly excited about the WSUS proposal after my attempts at dissecting it in my masters thesis. This will be good for microsoft in the long run. Yay to the EU.