This just in from FantasyCon:
The Primarchs stuff is self-explanatory, but the SMB novel that Laurie announced is about the Battle of Miral, where the Scythes of the Emperor met Hive Fleet Kraken in battle after the Devouring of Sotha.Facebook said:- Guy has written a Primarchs novel, 'Perturabo: The Hammer of Olympia'. It features the early days of his upbringing by the Tyrant of Lochos, and also his vengeful decimation of the populace once they rebel against the Imperium later on.
- Gav is writing a Primarchs novel focusing on Lorgar.
- David is planning a Primarchs novel focusing on Ferrus Manus.
- Laurie announced his SMB novel 'Slaughter at Giant's Coffin', which while 40k also has many links to the Heresy and particularly the events surrounding the Pharos.