I think you can take what Amazon say with a pinch of salt.
this just copied from Terry and Rob.
12 March 2009, 10:31:
Unseen Academicals is the next Discworld novel, which is due to be published in October, but we haven't finished it yet.
from the Horses mouth so to speak.
He willnae tak' a drink! I think he's deid! , on the other hand though A Midgie in yir hand is worth twa up yir kilt.