David Cumps is playing around with XAML and skewing UI controls. He found a bug which causes some rendering artifacts when doing a skew of a listbox. I tried some of his XAML out on the latest and greatest bits and didn't find the bug. So, this is either a video driver issue, or it is something that we've fixed since the PDC. Here is a (badly encoded -- thanks mspaint.exe) gif of a skewed list box:
