This is literally just an upgraded version of the image search that's been around for years.
No one had a problem with google pawing through our images, but now that it's looking at our faces, we're all rip? We gave websites permission to host our images, if anyone actually read the Terms of Use, most websites that host images (imgur, facebook, almost anything) those images are free domain essentially.
You've pretty much already agreed to do this, it's just a matter that they haven't started doing it yet.
I think it's sick, so long as we don't go overboard with it it's going to be awesome.