I always wondered when Google would come up with a way for the end user to moderate up and down certain search results. For example, about.com has garbage with a ton of ads. Unfortunately, about.com always gets to the top of search results for basic computer queries.
It looks like now Google will address that with these moderate up and down keys next to the search results. They call it SearchWiki. They're pretty explicit about how this only affects one's own results - but I'm confident they're just trying to not incentivize SEO black hats from using click farms to moderate up their placement. In the end, Google will have to consume this information and modify search results accordingly (I hope).