I was just doing some regular browsing in IE and wanted to check a page in Firefox. So I did the same search in FireFox and, wait, different results...I thought maybe I had caught yahoo in a ranking update, but I tried again and the results were the same in IE. What's funny is that it seems to 'tailor' results depending on what browser you are using.
For instance, when I search 'bugs', in IE I get results about insects and real bugs, but when I do it in Firefox, I get information about computer bugs, since Yahoo must figure FireFox users are nerds! :)
Maybe it's just me, but test it out. I tried it for a few different keywords and it still seemed to stand up. Also, when I went to more specfic searches (i.e. over one word) the results seemed to be the same, but for one word search they appear to be different...