It has recently been revealed that WotC has been negotiating with AEG to do it.
I don't know the validity of the source. However, it does sound strange. The original report says that due to a clerical error WotC's itinerary of discussions with other companies was included in a d20 handout. Supposedly discussing licensing Dark Sun to AEG was one of the meetings listed. Also listed was a meeting with White Wolf on a Top Secret licensed product.
It may be 100% true, but it sure sounds awful fishy to me.
The fishiness I was referring to wasn't that AEG is negotiating for the license to do Dark Sun. I was referring to WotC "accidently" releasing their itinerary in such a way.