Internet search engines are tapping into the brains of your friends -- well, more or less. You'll soon be hearing a lot about what's called "social search." For instance when you do a Google search, hits from your Gmail show up in the results. Google is now expanding that system. Over at rival Bing, the Microsoft search engine, they're doing something more interesting. Do a search for info about, say, athlete's foot and Bing will also check what friends on Facebook are saying about fungus infection. What are the good and bad implications here?