What does Google get from +1?
3 comments
Google can track your activity on every website that uses the +1 button. I'm sure you can figure out why that would be useful?
Data for advertising?
Data for "Sparks" to hook you into G+?
More data about your interests and browsing habits (great for serving ads against), crowdsourced site rankings and trends, stickiness when a user bookmarks a large number of sites with +1
Is it usable for anything else?