Just found this, published in March 2011:
Terry Pratchett has signed a deal with Prime Focus Productions to bring the 'City Watch' subset of his Discworld novels to television. The deal will allow for an ongoing TV series featuring new adventures and episodes based on the Ankh-Morpork City Watch, commanded by Sam Vimes and made up of a mixed group of humans, trolls, werewolves, vampires, zombies, golems and dwarfs. Exactly how this will work - whether they'll start with an adaptation of Guards! Guards! or a new introduction - is unclear at present.
Pratchett was working with the BBC on a similar project a few years ago (hence why none of the 'City Watch' books have been optioned by Sky for their TV movie adaptations) but pulled out after the BBC refused to allow him a say in the running of the series. It's unclear if a broadcaster is interested in the new project, but given that the head of Prime previously worked on the Sky adaptations, we can guess that Sky will at least give it a look.
Meanwhile, the next Sky novel adaptation, Unseen Academicals, starts shooting in the near future. Pratchett's next Discworld novel, Snuff, comes out in October.
Bugger the BBC. Buggrem, I say.