It is some of a problem. Especially because I must keep display strength to a minimum to save battery. But it works. I use the colorsheme morning (think its part of solarized) in Vim and let the sun hit the screen. And then when the screen gets to hot I move to the shade and use Jellybeans colorsheme.
Really wish there were decent ultrabooks with e-ink displays for working in the sun. This is the only commercially available product i've seen - http://ubuntuforums.org/showthread.php?t=2125333