The problem is that tech-savvy user will consider that evil and will be annoyed. They need the goodwill of the community to be able to hire very good programmers.
Facebook, on the other hand, is based on the users voluntarily and involuntarily (through friends etc) providing their information and isn't so discreet about it's attempts to leverage this data to profit.
This is known even by non savvy users (personally, I've met a lot of non technical people that were worried about Facebook's collection of data with regards to personal rights/privacy, but haven't once heard about Google's tactics) and has bitten them before, e.g. Beacon.
So I feel that Google won't be stigmatized by such a move, considering it's against an opponent perceived by the public as more evil.