I would add that notice and notice is not a silver bullet; it's just the first step in a process by which rights holders can go after those they allege are infringing. The role we play through notice and notice is to send the notice off to an alleged infringer on behalf of the rights holder. Then the rights holder can use that when they decide to take that alleged infringer to court.
We are an essential part of the process, but we can't make the whole process work by ourselves. There's a responsibility on the part of the ISP, and a responsibility on the part of the rights holder. We believe that the act very clearly defines the role of each player and stakeholder in the overall copyright regime.