Just heard the following over at Welcome to Chaos Dwarfs Online - Your Unofficial Home for all things Chaos Dwarfs:
Tamurkhan is due out in July 2011. The Chaos Dwarfs were primairliy designed to be used as a contingent to add to the Warrior's of Chaos army, however the book contains a FULL playable Chaos Dwarf Army List with many options and upgrades.

The new Chaos Dwarf infantry (Infernal Guard) are Chaos Dwarf Slaves that are forced to wear the full suit of armour and full face helmet before being unleashed on the Chaos Dwarfs enemies. The champion has no full face helmet which is a reward from his captors.

Most of the warmachines had two pages of rules/background/stats etc some of this stuff is going to be complicated to use. The Warsmiths also had a huge amount of original rules and exciting options.

Warmachines can be connected to form a seige train, however it costs a ton of points and won't be used unless you are playing 'ard boy lists (3000+pts).
The guy had been to the forge world open day