Google has experimented with search features that let users vote on search results, and/or recommend other results than those given, since late 2007. They generally bucket test these features (meaning some small percentage of users, randomly chosen, see them), and if testing goes ok, they move them into the optional experimental area where any user can add them.
One of our readers, Adrian Pike, may be included in a new bucket test that includes a variation of last year’s experiment. The screen shots he’s sent show an up arrow and an X. Clicking on the up arrow turns it green and adds to the total vote count at the end of the search result. The main difference between this and last year is that it looks like users can change their vote. If anyone else sees this, please let us know.