I have never joined facebook, and am thankful for this. But I was suckered into joining linkedin, and when I saw they had uploaded my contacts list from my gmail account, I had to leave.
As you may know, they send all of your contacts who aren't members messages saying '<person name> invited you to join their network on (linkedin|facebook|twitter)'. Sometimes they even mail to 'remind' you again a month or two later.
I don't think users necessarily realize these messages are being sent ostensibly on their behalf. In my view these large, successful companies are growing their user bases through spam.
I know - I had family members asking me 'what this linkedin thing was'.
That's when I quit.
(I don't remember giving them my password, however the link to send someone an invite is actually a link to send EVERYONE and invite, and apparently that includes the contact list they uploaded (or from my point of view, stole))
How evil would it be if they tried using your LinkedIn password with your profile's gmail address to access your gmail contacts? Probably 90% of people would have both passwords set to the same thing.
Pretty evil. I wouldn't be too surprised if they did, but that's a shitstorm waiting to happen, and Linkedin is still trying to uphold their 'professional' image.
Personally I don't have my Gmail address as my contact email... but I doubt many people own their TLDs with corresponding mailboxes.
I don't think users necessarily realize these messages are being sent ostensibly on their behalf. In my view these large, successful companies are growing their user bases through spam.