I've just received the new Apple TV in a developer kit. Thank you Apple! :-)
The Apple TV does however not start! I only see a reset screen which tells me to connect the Apple TV to my computer with USB. I have done that and started iTunes but it is not possible to do a factory reset. I think the problem is that since the new Apple TV is not actually relesed yet there is no factory reset information available in iTunes at this point.
I have upgraded iTunes with the latest release but still is is not possible to do a factory reset.