I can't say I'm overly concerned. There's a perfectly good replacement for every single Google service that I currently use. If they start abusing people's data, I'll just boycot their services completely. If enough people do this, it opens the way for competition who will be more careful with our trust. Google will really need to consider their moves here.
I use to work for a company that had a warning message every time you logged onto your workstation, it basically boiled down to, only send emails / instant message you would be happy to have re-published in a national newspaper.