Um, I think EVERYBODY is missing the truth here (the accessory makers, MacRumors, the forum people, everybody). The truth is that Apple will be coming out with a 30-pin to 9-pin ADAPTER that makes old accessories work with the new 9-pin connector. NOBODY will be left hanging at all this holiday season. Not customers, not accessory makers, nobody.
The adaptor will take up space, and the iPhone 5 will be taller. I doubt an iPod stereo systems will work with an iPhone 5 using an adaptor.