I recently had the pleasure of meeting Alex "Sandy Mitchell" Stewart at a book signing at my local GW store and so I took the chance to ask him for any tidbits about the forthcoming Dark Heresy novel "Innocence proves nothing" (the sequel to "Scourge the Heretic").
The book should be out for Games Day '09 (not big news) and in his words contains a lot of "running and fighting and death"
Most of the action is set during a looooong space journey (or rather two separate space journeys as the characters are split up) with the main group of acolytes aboard....the Misericord. 
Should be cool.
He's currently writing a new Ciaphas Cain short story for a special Games Day book and then he'll begin work on the next Cain novel which will also feature some of Cain's activities with the Reclaimers Space Marine chapter in an adventure he described as "Ciaphas Cain and the marines assault a Space Hulk" (I suggested that that sounded like the toddler's board book version). That and the following novel will cover what Cain got up to during the second Tyrannic War. He also implied that it may feature the Tau working with the Imperium against the Tyrannids , whilst forces within both Imperial and Tau sides act to try and destabilise the loose alliance. Meanwhile the Reclaimers work to their own aggenda. It all sounds like jolly good fun 