Here is a quick post on how I fixed my retina resolution on ubuntu.
Today I installed ubuntu 13.04 on my MacBook Pro Retina (10,1). Everything worked fine out of the box, but ubuntu has set the display resolution to 2880x1800. Although I looks pretty sexy to have such a high resolution, I thought it was a bit to much. I played a bit with different settings and I found that a scale factor of 0.6x0.6 works the best. Here is a command to change it:
xrandr --output eDP-2 --scale .6x.6