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 receipt of the engine source code.
Update
The latest news (as of 11th October 2005) is that the source code has been successfully located and we are now simply waiting for it to be sorted and sent to us.
This will hopefully happen... 'shortly'. :)
Summary
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.