@cbae: There has to be some software patent holder preventing them from doing this. When using the mouse, the metro environment feels like anything but fluid. And then there is the issue of orientation. Mouse wheels are orientated vertically, while everything in metro is horizontal.
Yup, it took a little while to get it ingrained in my head that the horizontally scrolling live tile screen can be scrolled with a vertically spinning mousewheel. I think that in any Metro/Modern UI app, the developer should allowed to specify that certain controls allow kinetic scrolling using the mouse like in Bing or Google maps. The live tile screen should be one such place where it makes sense since scrolling accuracy isn't all that important on this screen.