A couple of guys work for Google and then leave. They then open a startup that is a social Q&A service.
The gist of Aardvark [vark.com] is that it looks at your social graph (a representation of your online connections with people), sees what you know (as self-reported and evident on your various profiles and content), and then submits questions for your consideration from other users. From vark.com:
When you want trusted information — product recommendations, travel suggestions, local tips, or career advice — a real conversation with a friend (or friend-of-friend) can be much more helpful than searching the web.