Windows 8 - Fancy Progress Bars API?
For all those interested, I have implemented a WPF version of this progress bar avaliable from my blog here (linking so I've only 1 place to keep a valid active link). I decided it was better than waiting for something available only on Windows 8 or not available at all. I hope you find it useful.
Unfortunatley I wouldn't expect any Windows 8 related API support until the release or a few weeks before Windows 8 is rolled out. It might even be included within a new Visual Studio service pack some time in the near future.