Well, I finally jumped through all of the code/registration hoops. Game has a Crucible Pass that is listed on the backside of the manual (Not Season Pass). Game also comes with a thq promo code that you use at darksiders.com/tomb. Once you enter the promo code on the site, the in-game code for the tomb should be sent via email, when it's available.
When you start up the game you are prompted to register for the darksiders community. This is the same login for the thq.com site, if you already registered. After registration you are sent an email to retrieve two free pieces of equipment (Van der Schmash and Mace Maximus). The links I was sent in an email to retrieve these items are currently broken. I'm guessing this won't go live until the 14th.
I'm guessing the season pass will be emailed to me later. Hopefully some information about the season pass will come out on the 14th, for the people who pre-ordered from the THQ shop.