Scrolltabs is a nice concept. But i do not know, if it could improve the browsing experience because a lot of pages are very long.
For the next version of IE, I would like to see thumbnail previews for tabs á la Vista taskbar and a "Flip"-like preview when switching tabs with CTRL+TAB.
BTW: What I don't like about the scrollbars is, that the minimum hight of the scroll button is to small (wasn't it a square in older Windows versions?). On Vista it is nerly impossible to scroll through large documents on a tablet pc.