Now we have the Pixel desktop it's very similar but you need to edit the following file...
#@lxpanel --profile LXDE-pi
@pcmanfm --desktop --profile LXDE-pi
@xset s off
@xset s noblank
@chromium-browser --kiosk --incognito http://www.bbc.co.uk/
Make it look like this by commenting out the lines for lxpanel and xscreensaver then add an entry to start Chromium at the end opening whatever page you'd like Chromium to start with.