Windows 8 milestone 3. The latest discovery is that Aero in Windows 8 will be able to automatically adapt itself to match your current wallpaper image. It's a bit like what Windows 7 already does with your taskbar icons: if a program alert needs your attention, the icon will glow using the predominant color (e.g. Firefox should glow orange).
And yes, you can already make Windows 7 behave this way if you like. Over at CodePlex, there's a little program called Aura that parks itself in your system tray and automatically adjusts your window borders to compliment your wallpaper images. The effect is quite nice, and you can try it out by minimizing your windows and cycling through your theme's wallpapers (right click on your desktop and choose next desktop background).