Amazingly insightful. Audience and user segmentation, I believe, is the key to unlocking value from community driven publishing and media models and businesses. The ability to segment, in turn, requires a discrete level of correlated user, usage, media and context data. It needs to be collected (efficiently, which the right detail to drive its organization, which I submit is not trivial), stored, analyzed and delivered in actionable pieces, to publisher and advertiser.
I would submit, that Yahoo hardly needs to do anything drastic, except, that it needs to reorganize its entire portfolio into Segments and Lifestyles, and align the 4Cs of each segment, so that the people interested in advertising to a particular segment can reach the community in a focused way, in Context. If they want to sell Groceries to people reading recipes, they should be able to reach them right there. Or, if they have Gadget Geeks researching a cell phone, they should be able to access that eye-ball, in Context.
While this level of analytics is only now beginning to be available, it is, as I have written before, remarkably powerful.