A few snips from the article...
Microsoft is loosening restrictions on under-the-hood information needed to create products that will complement and compete with its own. In addition, with this highly technical announcement, Microsoft pledged support for competing document formats, industry standards and interoperability with open-source software.
It published more than 30,000 pages of technical documentation describing Windows client and server communications protocols that previously required a trade-secrets license from Microsoft. Communications protocols are the way computers communicate over a network.
"Developers will not need to take a license or pay a royalty or other fee to access any of that information," Ballmer said.
Here they are ..Windows Communication Protocols
Some of the interesting ones to me are the MS-KILE - Kerberos and [MS-PAC]: Privilege Attribute Certificate Data Structure as well as the Certificate\PKI ones. Very very cool.
key: protocol documentation