Note board webpart - Social Collaboration feature

Here is some good links expaining in depth.

 

http://amolmeshe.blogspot.in/2012/10/note-board-webpart-few-points-to.html

 

http://msdn.microsoft.com/en-us/library/ff407953%28v=office.14%29.aspx

 

http://social.technet.microsoft.com/Forums/sv-SE/sharepoint2010programming/thread/709cb31d-6a1b-4903-a703-f6b2d7bf3738