Can Yahoo harness the power of its 165 million registered users to do what no company has done before -- successfully bridge the blogging market with the world of social networking? The Internet giant vows to do just that, starting March 29, with a service called Yahoo 360. One thing that might make this work: the deep wells of subject-specific content that Yahoo has aggregrated through the years. Content can help to organize communities, and blogs -- especially group blogs -- can create an ever-expanding landscape for these communities. And don't forget the business model -- more landscape means more real estate (advertising).