The real problem I have with this is feature is it being tagged as innovation by this article, Douglas.
I'd really like a bit more care in the use of this word, particularly when it comes to a technological website. Frankly, innovation isn't the thing that comes to mind when adding already known features to a search engine (like social web features). I think of Lego pieces, of plaster, or a house annex if you will. Not innovation.
Innovation would be, for instance, to change the way results are presented to us. More and more the current uncategorized (vertical shopping list) web search results is becoming cumbersome. I'd like to hit "King Kong" on a search engine and this resulting in a categorized list of results, separating films, from sports or songs.
Innovation is what Blekko is trying to do, for instance. Or the defunct Cuil tried to do. Innovation isn't grabbing Lego pieces and making a castle. It's creating new Lego pieces or do things for which Lego pieces weren't designed for.