Still, if any developer works overtime, it's Polyphony. They're absolutely anal about every little detail. My thinking is that GT4 will be huge, and that everyone will still be happy with it this fall (mumbling and grumbling to themselves as they unlock 500 cars). And then, Sony, which is working on a new dedicated online service, will transfer all that knowledge and technology that Polyphony has been working on for so long to another little something. I suspect Sony will launch its new online system with an online version of GT next year sometime, and that will be the flagship title. Just a little speculation, of course, but hey, you know Polyphony is doing something with all that online technology (which, it admittedly had a hard time getting to work on Sony's system). They're probably unofficially doing all the testing for the service with that game as the test model.
