Ok...so I know it's easy to seem a bit paranoid but there is more than sufficient reason to worry about Facebook and Google+...
A recent article reveals that social media are regularly used by law enforcement to target individuals in the name of homeland security and emergency relief details here.
...and recently installed face recognition software on Facebook (where if I remember right I was asked if I would include permission to apply this ability to photos of friends) will eventually lead to anyone being able to access a whole load of personal information, including your social security number from a simple photo of you taken in the street... details here..
This leads to a heightened ability to steal identities (not to mention stalkers) again, details here.
Now... it is totally stupid to say, as some have recently, 'I have nothing to hide'... duh!! .. your address? credit rating? your bank account? whether you live alone or not? details of you health? past relationships? where you buy your underwear? .... there is a limit as to how much information any of us want available online.
This is not a scare story, this is today, now. As Google+ insist on real names now, the time will come when real photos will be insisted on too... because? Because the information is worth money.
Forget advertising revenue... that may pale in comparison as Google+ may have, as it's main income source, the law enforcement agencies..... maybe not today, but soon.