Dark Sun was my favorite campaign setting for 2e, until Planescape came out-- but until the Psionics Handbook came out, it was impossible to play 3e Dark Sun, and by the time the Psionics Handbook came out, I lived 600 miles away from my gaming group.
If a good 3e campaign setting book for Dark Sun came out, I would be all over it-- almost as fast as I'd be all over a good 3e version of Planescape.