I have no direct experience of using a Kindle, but according to the ads on television there are no problems with reading from it in direct sunlight.
Quote from a review:
"Unlike LCD screen, you can read Kindle screen in direct sunlight with no problem. Since having Kindle I spend part of my lunchtime reading under the tree in broad sunlight. On the other hand, I can't read it in the dark as I can with an LCD screen, Kindle always requires light, as a real book does. Fortunately, a clip-on reading lamp won't cost you an arm and a leg($5-$10, cheaper if bought bundled with a protective case)."
Source:
http://www1.epinions.com/review/Amazon_ ... 1669567108