I successfully got my BB (Spokane Valley, WA) to PM God of War 3. The thing is they have always been totally cool with PMing GCs, maybe because less people know about/abuse it, but it was kind of weird: back when MW2 came out, I was able to get the game for $40 (they deducted the GC, like their policy says). Today the girl sold me the game for $60 and gave me a $20 gc. She was nice enought to transfer my preorder from the other store across town (I perordered it there, but there's no TRU out there to match) so I was able to get the game + $20 GC for $58, but when I looked at the reciept, the game rang up at $40, and then she sold me the GC for $20. She could've let me go with just the game for $40, but before ending the transaction she tacked on the GC, and basically made me buy it when I didn't need/want to, but I didn't make a big deal out of it cuz my dad bought some cds which used the majority of the card, then he gave me cash back for it, so I still saved 20 bucks.
Also, they may not fight me on it cuz I'm literally in there ALL the time, and I'm a silver member. I assume I still got the 500 bonus points...