Make sure you check out their website as they are a bunch of guys totally dedicated and obsessed with the Heresy!
Also, we had a lot of members of the Heresy30K Forum there with some highlights:
Book 6 is called Retribution
5 new stories and battles
One has DA, one BA and one Scars
New Legendary missions, new forces
Blackshield and Knight errants
Expanded shattered legions
Combinable Rites of War for the Shattered Legions!
New Rites of War will be based on Black Library events
The iron warriors have one based on a short where they were charging between their own bombardment.
Word Bearers have a Gal Vorbak one
Andy Hoare: There are going to be around 30 Rites of War released in Book 6.
Thousand Sons will have their own Legion specific psychic powers
Bedford has started work on Tyrant Siege (Although last event weren't they supposed to be mostly done?)
Atrementar rules are in concept
Much thanks to Battle Bunnies!