The issue of social search has a lot of mindshare. Some think it is the future of search. I disagree.
One of the things that made search successful anduseful early on was scale. Instead of having to go to the librar or ask your friends you can effectively canvas the connected world.
I find the notion that friends' recommendations will replace that as nothing short of bizarre. It's like a huge step backwards. The argument is that you can filter out the garbage as your social graph will provide a level of curation.
Let me give you a concrete example. If I wanted t buy a camera I'd stil need t go to dpreview and other sites. It's highly likely that my friends don't really know a lot about this (but some will have an opinion anyway).
This same idea of human curation is behind such sites ad Mahalo and the garbage sites themselves to a degree. Of course at some point computers will be powerful enough to generate this garbage content.
Blekko's idea of slash tags s interesting (to a degree) but if it's successful its easily reproducible. Google is still in the box seat here but of course that's no barrier to a link-baiting TC title.
Personally I'm an optimist. I believe that, much like email spam, the garbage from AC, DM and others I'd a transitional problem (email spam is basically a solved problem now if you use a half-decent email provider). If they succeed we won't be able to find anything. I don't believe that'll happen so these services are therefore doomed.
So betting on Demand Media is (to quote Tyler) like betting on the Mayans (meaning betting they're right about the world ending in 2012: it doesnt really matter if you're right).
So my money is on Google being the better Google.