Watch Chris Slemp's video* for an overview of TN/MSDN's "social platform" that includes:
Community Content (ak.a. "wiki") - for example see http://technet.microsoft.com/en-us/library/cc753637.aspx
Forums - for example, did you know the Scripting Guys have a forum?
Oh yeah, search is now part of the social platform
*Hey, who's profile is that on the screen at about timecode 2:07?