Yahoo is a content company, google is a search company. Unfortunately, being a content company is more labour intensive than being a search company, especially when you are trying to be an international company.

Yahoo needs to get off the content train, sell some of its premium services and failed integrations (delicious, anyone?) and push harder on the "your mail contact list is your social network" push that they have going. Fortunately, they have a lot of good properties. Unfortunately, their integration is absolutely abysmal.