I wouldn't consider the Nexus One obsolete. The whole point of the N1 is that it has an unlocked bootloader, so you don't need Google's blessing to run custom

I wouldn't consider the Nexus One obsolete. The whole point of the N1 is that it has an unlocked bootloader, so you don't need Google's blessing to run custom roms or newer versions on your hardware. There are already ongoing efforts to port the 4.0 SDK images to run on the Nexus One and the Nexus S, and I guarantee there will be even better options once the source code is released. Use the freedom you paid $600 for to run ICS on your phone anyways.