Did you notice that you can now vote for or remove search results in Google? Maybe not, they're grayed out boxes next to the results. At this point, it only affects your results - but such potential in bulk!
If you've ever searched for Kentucky artists (and I have lately, for a grant), did you really want ALL the tattoo artists in the state? Change it to Kentucky Art and you get lots of names. I can now remove them from my results, or promote the really good sites.
What's really exciting is what (I imagine, but the Google Guys are no dummies) is going on behind the scenes. By associating the terms I'm using what I'm doing with the results, I'm in effect voting on the semantics, separating the types of art. For now, it's just mine, but multiply by millions and you may, fairly soon, be able to search character and get results clustered by typographic, moral, and cartoon even when those terms aren't used in a page.
An enormous semantic thesaurus, using current terms that we really use and not LC faceted terms from the 50s or 60s. The ultimate (for now) use of the hive mind, without the hive realizing it, not unlike the SETI screensaver that ran int he background analyzing data.
Think of groupsourcing as distributed computing. Not all the results are gold, but like ReCaptcha, the cumulative results are good. And good is good enough, right?