I've been working on Visual Style for Windows 8.1 recently, titled Polymer. I'm not currently able to work on it, but I thought I'd release the (unfinished) Start Menu and button in advance. It's currently only available as a SKIN7, but I will probably create a SKIN version as well at some point. Here's an image of the menu, as well as the button in all 3 states:
(I have fixed the white text on the white background since this image was created)
And here's the SKIN7 itself: Download