Rhianna Pratchett, daughter of Discworld creator Sir Terry, and a successful writer herself, working on the recent BioShock and Tomb Raider games, among others, has announced via her twitter that she's adapting The Wee Free Men, the first in the young adult series of Discworld books featuring apprentice witch Tiffany Aching.
I have a lot of hope for this. Pratchett said about a prospective script from 2006 by Corpse Bride writer Pamela Pettler that he "frankly thought was awful. It seemed to be Wee Free Men in name only. It had all the hallmarks of something that had been good, and then the studio had got involved. It probably won't get made." He announced in 2009 that he'd got the rights back.