I'd be offering quite a limited service - not some sort of anti-libel service. We'd just get streamlined at removing specific software from specific websites, and then go to those developers and say 'Hey, we can prevent people stealing your stuff.'
As an iPhone developer, I'd certainly think about using you if we had something with significant pirate traction (Especially something that utilized server resources).
Make sure X Y and Z are all in the realm of good stuff.