I think this is a great premise. Basically, legit purchases are treated with respect. Only people who pirate would be subject to penalties, as they would be subjected to in any court of law if they shoplifted or stole goods in general. I don't know what they will be charging as a fee, but I imagine it will basically the full price of a license plus lawyer fees and a bit of interest for usage.
This sounds like it may operate similar to how those red light cameras operate. Basically, a law firm agrees to go after offenders with the understanding that their direct costs will come from any restitution. While they won't catch everyone, once people realize that downloading via p2p networks is not anonymous and that they can in fact be located in many areas legally it won't be long before some people will be gun shy about downloading. The latest rulings on Limewire only reaffirm the thin ice people are skating on.
Anyways, this won't stop piracy, but I think it's worth trying, especially if legit customers lose nothing in the process. I will definitely vote with my money in favor of CDProject this time around.