Welcome to the patterns & practices Security Wiki! This is where we put our latest thoughts and discoveries in application security. We are constantly talking to customers, industry experts, and security experts inside Microsoft to bring you the latest and greatest. Here you’ll find emerging practices, guidance for application scenarios, security engineering, threat modeling, technical guidance and more.
Author: Microsoft patterns & practices security team.

http://channel9.msdn.com/wiki/default.aspx/SecurityWiki.HomePage

Thats by the way a good moment to link to the Patterns And Practices Security Guidance page on MSDN:
http://channel9.msdn.com/wiki/default.aspx/
SecurityWiki.PatternsAndPracticesSecurityGuidanceOnMSDN

Urs