via Stickmonkey:
January: Warriors of Chaos
February: Dark Angels
March: Chaos Daemons / Daemons of Chaos
April: Tau Empire
May: High Elves
June: Eldar
July: Apocalypse
August: Lizardmen
September: Blood Bowl
October: Space Marines
November: Dwarves
December: Hobbit
January: Tyranids
~That would be TEN Codex/Armybooks in 2013 if it holds up, only about triple the standard GW release rate. Something has definitely changed within GW.
An interesting note, even with a production rate of this speed (assuming GW could hold it up permanently), this would result in a complete refresh of every army book in both WFB/40k every 3 years. Also, you will notice that this schedule is front-loaded with signs of slowing. It has 7 books in the first half of the year,and 3 in the second half.