So phoning around to a few of the blockbusters in my area I have found the deal only applies before the game's release (in other words, only for pre-order). So at the moment this only applies to God of War II, however one of the people told me that they do this ever couple of months with new games to pre-order. She suggested I phone in every month to see what game they are offering this deal for. From the sounds of it, it looks like they plan to continue this for quite some time.
For those who want to get God of War II with this deal, here is a semi complete list of compatible games (note: the minimum trade in value will vary from store to store):
Forza Motorsport (Xbox)
Syberia (Xbox)
TMNT - Mutant Melee ($6)
Gun ($6)
From Russia With Love ($6)
Midway Arcade Treasures 3
Forza Motorsport
Burnout Revenge ($6)
DT Racer ($8)
Suzuki TT Superbikes ($8)
Rebel Raiders : Operation Nighthawk ($8)
Mario Party 5
Kingdom Under Fire: The Crusaders
Prince of Persia: Warrior Within
Serious Sam 2 - $8.00 TIV
Scrapland - $8.00 TIV
Dead to Rights 2 - $8.00 TIV
American Chopper 2 - $8.00 TIV
Classified: The Sentinal $6.00
Pariah $8.00
Need for Speed Underground 2
Call of Duty: Big Red One
Resident Evil: Outbreak 2
SSX on Tour
NHL 2006
Viewtiful Joe 2
Hunter: The Reckoning
Stake
Blood Wake
Magic The Gathering: Battlegrounds
The Punisher
Silent Hill 4
Wallace and Gromit in Project Zoo
Spy Fiction
Genji
Project Snowblind
Lugui Mansion ($8)
Waverace ($6)
Harry Potter ($6)
Nintendogs ($8)
This was compiled from the RFD thread posted by firestorm.