If you want to see which is the winner out of google and yahoo, Go to this page: http://forums.digitalpoint.com/ (nothing but Digital POint itself) Then see how many people are online in Google and Yahoo forums : something like 10 in Yahoo and around 70 in Google.......so it does not need any explanation i think !
My opinion is that it is harder to "game" the Yahoo system, and therefore they could have more ...pure search results. -unaffected by cheap SEO methods.
I don't think that yahoo can "catch" from behind google. Only if they will think a few steps ahead. http://www.findhost32.com/