Paul Adams, the previous social research lead in the Google UX team, explained why context matters in this very interesting presentation (12 months old!):

http://www.slideshare.net/padday/the-real-life-social-networ... (discussed at http://news.ycombinator.com/item?id=1867807 )

According to his blog ( http://www.thinkoutsidein.com/blog/ ), he now works at Facebook, and focuses "on researching and designing better ways for businesses and people to communicate and interact". My guess is that Facebook is already preparing its response...