There is some data that points to Yahoo having a harder time during this recession (or whatever you'd like to call the economic malaise we're in). Data from early in 2008 showed that Yahoo tended to attract lower-income users. Those users are already taking the worst of the economic downturn.
Low-income users are also most likely to be wooed by Microsoft's pay-to-search incentives and programs like Live Search Cashback. Those programs may explain Microsoft's year-end rise in advertisers. The question is whether Microsoft can continue paying users just so it can stay in the search game. There's also data that shows lower-income users increasingly are turning to iPhones for their search needs, which plays into Google's hands.
So, given this dismal data, it may be that the biggest job of Carol Bartz is to determine how to dismantle and sell the parts of Yahoo to get the best value out of what remains. What a difference a year makes.