Athas dot org has done wonderful work on the conversion project, but I have heard that the official license is in another publisher's hands. Can anyone tell me whose hands, or what they plan to do with it?
Crothian is correct. Jim Butler of Bastion Press mentioned this in a recent interview somewhere. Basically, WotC is willing to license out old worlds to third-party publishers, but only on the condition that they (WotC) can be the one to publish the core campaign setting book for the world, with the support products published by the third-party company.
Apparently WotC "wised up" since letting SSS publish the Ravenloft campaign setting.
Anyway, since the campaign setting is always the book that sells the best, and since WotC would reap the profits there since they would be publishing it, licensing old worlds has now become a bad idea for third-party companies, since they'd lose money on the deal.