The latest Raspbian (September 2016) has a new Desktop called Pixel. You can download the image of the OS here: https://www.raspberrypi.org/downloads/raspbian/ . Write the image on a microSD card the same way as before.
So, what's new? The graphics is flattened making everything look 2D - not a bad thing. Epiphany web browser is making room for Chromium and uBlock Origin adblocker. Take a look at more detailed list of all the new features here: https://www.raspberrypi.org/blog/introducing-pixel/ .