The big news announced at GamesDay Baltimore 2010 is the next Forge World Imperial Armour book will be The Badab War Part I.
So what’s the Badab War?
From http://wh40k.lexicanum.com/wiki/Badab_War
The Badab War was one of the more serious rebellions in recent Imperial history, involving several Space Marine Chapters. Badab is a planet in the Ultima Segmentum, close to the border with the Segmentum Solar.
It will be released on September 27th, but I suspect that there will be copies at the UK GamesDay that is the day before.
We also saw pics of a Grot Mega-Tank to complement the already released Grot Tanks and an Eldar Titan.