A friend sharing my information is a totally different scenario. That person would have been entrusted with your information only after your consent. Since there is no legal obligation on his or her part to keep the information private (there is of course some social obligation) the person had every right to share it with others and on Facebook or Google. Unfortunately we are just beginning to realize the issues with such an open system where detailed documentation has just started, how we go from here is totally up to us. But I don't think we can hold Facebook or Google legally responsible for what our friends are doing, at least not yet.
Users might not be even aware of how the data is being shared, or if it's being shared at all.
I signed up to Facebook under a pseudonym recently, but with an old work email address. I only wanted it as a throwaway account. The auto friend suggests were there soon enough and uncanny. It took me a few moments to realise the links had been made through my email address. I had not shared address book data.
It became apparent that the suggestions were a result of other people's address books (not necessarily friends as it was a work address.)
Some suggestions were a bit of an enigma. I'm not sure how Facebook draws up these connections but I guess they'd taken friends of friends of those that had me listed in their address books.
What surprised me was that the address book data shared from the other accounts, was obviously kept with Facebook for later use. For some reason I thought it would be used once then thrown away (how naive of me.) It felt a little inappropriate to say the least. I felt my addressbook had been mysteriously revealed. This could potentially be abused (not sure if the suggestions came up, before I verified the address.)
Soon after, one of those suggested friends tried to friend me. I guess my account came up as a suggestion to them. A little revealing. I should have used a new email address to sign up I guess.
