However, I have a BIG feeling that link popularity counts, but in a weird way. One of my keywords is "car rentals" and the top site is Budget. On altavista, budget has 1105 links pointing to it. However, they don't use themes and only a few of their pages mention car rentals. So I am starting to believe that link popularity is a major factor, but maybe just for the top site? If you look at results, the #1 slot tends to have the most links pointing towards it, and from then on it seems to be all themes.
Just some thoughts.