There has been ton of talk about search engine market share over at the forums and search engine related blogs. All saying that Yahoo has a ~30% share and Google has about a ~39% share. But what really matters is your traffic patterns.
Why is it that most of of the sites out there have 70% of their traffic from Google and 10% from Yahoo? Are the SEOs only optimizing for Google? Does search engine friendly design only apply to Google?
There can be many reasons why one site gets more of its traffic from Google over Yahoo. (1) Keywords rank better for a site in Google vs Yahoo. (2) Your site appeals more to the Google type of Web user. or (3) Google just really does have a better market share, over the estimated 39%.
There is a thread on this at SEO Chat, visit the Yahoo! Traffic today!