What does Google get from +1?

[ulvund]

Is it for the search engine rankings? Is it for targeting to more clearcut demographics with ads? (which is a huge business)

Is it usable for anything else?

[jigs_up]

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?

[tilt]

Data for advertising? Data for "Sparks" to hook you into G+?

[schraeds]

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