Apparently, the next Discworld telemovie has been confirmed by Pratchett to be "Going Postal."

So out of curiosity, who could you picture in the roles? Here are my thoughts...

Moist von Lipwig- John Barrowman
Stanley- David Mitchell (Been looking for a Discworld character for him for ages)
Adora Belle Dearheart- Tamsin Greig or Selma Blair.
Groat- Bob Hoskins for some star power or David Jason because he enjoys the roles so much.
Reacher Gilt- Mark Mitchell, I saw him on "Round the Twist", he would make an excellent Reacher.
Ms Maccalariat- Geraldine McEwan
Mr Pump- Anyone with a nice deep voice. If Clive Owen can voice him and be cost effective, that would rule.
Vetanari- Jeremy Irons