Honestly, I think the lack of social graph portability on Facebook is a really good thing. Look how they messed up the Wall with these so-called social games. The day Zynga gets my social graph is the day I leave.
Google's posturing is really getting old. Maybe I'd take them more seriously if they didn't have their finger in every pie.
I strongly prefer to keep my social graph private, and reveal it only to people who are in it. However, Facebook declared social graphs public quite a while back:
"Now when you uncheck the 'Show my friends on my profile' option in the Friends box on your profile, your Friend List won't appear on your profile regardless of whether people are viewing it while logged into Facebook or logged out. This information is still publicly available, however, and can be accessed by applications." http://news.cnet.com/8301-13577_3-10413835-36.html#ixzz1SMg1...
So as I understood it, Zynga already has access to my social graph. But I'm not a Facebook privacy expert; I find the privacy rules confusing.
* or, with some granularity and tuning controls, maybe for example just your name and it's presence in photo tags from your friends library, and nothing else, would be included.