Am I being paranoid when I think that offering this "free" service is a great way to track people over even more sites and usually the most important conversion pages that don't have the usual google display ads. I don't see a big technological innovation here as it appears that mostly they are checking your cookies to see if they recognize you.
And there are a number of sites using Analytics, Adwords/Adsense, DFP and a number of other points of connection. They've already offered/bought recaptcha, all this does is make it easier for most people (who have cookies and JS enabled).