That’s the KDE Plasma Desktop – I am running it on ARCH Linux, but the new Kubuntu (which I have on my laptop, and looks exactly the same) http://www.kubuntu.org/ has the same desktop.
The wallpaper is from http://imgur.com/gallery/dbELn
The wallpaper is from http://imgur.com/gallery/dbELn
Incidentally, nice looking desktop! Which distribution is that, if I may ask?