So I had an idea... You guys are going to release a pack of cards every month? Or every week? That's a bit inefficient. If, for some reason, a lot of your graphic designers/designers leave the project, you won't be able to make pics for cards unless you steal them from other places. I suggest you run on a system of user-submitted cards. This way, you'll get a lot more cards faster. The problem is, though, not all cards are good. Therefore, you should introduce a voting system, where cards are voted on and if they reach a certain amount of votes, they are added to the store or whatever. Packs of cards would just pull random cards from a large database of cards. It would work a lot better and it would be more efficient.
Good job so far and great ideas! I'm really excited about using this and working with you guys (I do believe I'm designing your homepage? Not sure, though.). I really hope all this code is open sourced. You should let some other PMCers work on it so that it can grow bigger faster.