I wish I were on my desktop, but maybe someone else can give you a link to it.... but the Mozilla team put together a presentation why it makes sense in every aspect of the experience for the tabs to be on top, least of which is because it preserves context. You change the tab on the top, it changes the url bar below it, and the content below it.
It's true that tabs on top are more sensible structurally, but they fail in one big way: there's no place on the screen that shows the full page title. I look at my Chrome, and the titles in the tabs are all truncated. I go to FF, and the title of the current tab is in the window's title bar.
Edit, went and found it on my mobile (http://blog.mozilla.com/faaborg/2010/06/24/why-tabs-are-on-t...)
Or are you one of those people that like the way Americans record their dates? (http://1.bp.blogspot.com/_0B3Gz7CcrZc/TG3Fex66wvI/AAAAAAAAMS...)