According to this News.com report Yahoo! is planning an overhaul of its home page this month in order to please its advertisers. The company is not commenting on the design changes prior to release, which seems to me to be a classic example of top down Internet design.
This should be contrasted with Google.com, which has adopted something of a ‘bottom up’ form of design, whereby the company posts a beta test of features to get customer feedback and introduces the feature only if it meets with user approval. I know which format seems to be more successful at the moment, and which wins more user approval all round.