We are currently investigating reimplementing the 'Tinsel' engine, as used by Discworld 1 and 2.
Ender is organising this.
Status
The rights situation has been resolved, and Terry Pratchett and his agent Colin Smythe have approved the source release and future freeware re-issuing of the game.
We are currently awaiting news on the engine source code.
The last update (23rd March 2005) suggests there will be more definite action by Mid April.
In short, we have all the approval needed to move forward with supporting the game and making Discworld freeware. However Discworld is NOT freeware at the moment. It may be in the future, assuming all goes according to plan.
We may not be able to wing a DFSG/OSI compatible license on this one, although I'll surely try.