One thing to love about upcoming operating systems and its public beta releases is that eventually feature details and design elements leak and get distributed all over the web. You may remember how there were several prospective default wallpapers for Vista that made it to the web months before the OS release. Something similar has happened with OS X releases which also come with great wallpapers out of the box.
Now Microsoft is expected to unleash the first public preview of Windows 7 at their Professional Developers Conference this week. Some details have leaked already, but nothing to share just yet in terms of UI elements except for this PDC wallpaper that all computers at the conference are using (courtesy of istartedsomething). I have been using it for the past few hours and I had to recommend it. Nice colors, blends well and is a bit flashy (Vista style) without being too distracting.