John Battelle has some interesting notes about Yahoo's push towards becoming a marketing platform, partnering for promotions by drawing on content from all over their huge network of sites, much of it user generated:

The company will tie together its disjointed properties — such as search, groups, Flickr, Answers, avatars — to lead back to pages about a certain pop culture topic — for instance, Nintendo’s Wii.

Is this a credible alternative to the advertising platform that Google has built? They're both aggregating eyballs and attention but in distinctly different ways.