Heh, I was joking around a little, but I hope you are right. The stuff SJ said about protecting the platform and signed apps makes me a little nervous. Those things don't mean Apple has to charge $, but they might not be able to restrain themselves.
I wouldn't mind a nominal fee (in the hundreds of dollars, not thousands) to, say, buy the SDK or a certificate to sign apps. But it would really stink if Apple took a piece of every app installed...
Everybody is assuming that the digital signatures are intended as a way of locking everything down so that nobody can do anything without Apple's active review and consent. And perhaps that's true to some extent. But I'm hopeful that it's only part of the story.
Maybe it isn't totally a case of risk prevention. Maybe there's also an aspect of blame assignment:
Rather than imposing corporate editorial review, limiting the developer's ability to create content, maybe Apple will give away digital signing utilities to everybody who asks for one. People can sign all their own apps and just drag-n-drop them into iTunes for installation. The catch would be that every digital signature contains an identifying tag with which can be used by authorities to trace any malicious code back to the individual who created it.
Perhaps Apple would institute multiple levels of digital signatures, so that the non-reviewed code is prevented from accessing some of the most critical components from a competitive standpoint, such as the microphone of Bluetooth -- if you wanted to access that stuff, you'd have to submit your code to Apple for review.
But if you didn't need access to any of the "restricted" systems, then the free digital signature would be all you'd need - and the fact that it would be uniquely traceable back to you would be enough to keep you honest and not do any intentional harm to users' security or privacy.