I think that at the beginning Yahoo will offer beta testing of YPN to most influencial bloggers and writers and will artificially set the payout to high levels so that these people will be marketing for free YPN to all other publishers. Some people say that Yahoo is moving too slow with YPN but I don't think so. Yahoo is a powerful corporation that has much more diversified income streams than Google and Yahoo really can beat Google in this thing that is most important to Google: contextual advertising.
So I predict, that Yahoo has chances to win over Google although it may depend on when Microsoft will launch some contextual advertising for nano-publishers... if Microsoft will launch late (what is likely knowing their problems with Longhorn/Vista), then Yahoo really can decrease significantly income stream of Google...
