Sounds like a fake to me.
it sounds fake, for a few reasons:
1. the heat output. two G4's chuggin' away under a case less than an inch thick is bound to cause problems.
2. power consumption. no battery could stand being drained by two G4's for very long. we would probably see drastically reduced running times, like from 4 hours to 1.5 hours.
3. Unfeasability. Stand back and think critically about this for a moment. Who in their right mind would put two of the most powerful processors into a thin laptop? It doesn't make sense. Thats not to say that Apple wouldn't be the ones to do it, but I just think they won't.
I personally would really like to see this happen, but I don't think it will, there are just too many flaws. So for now, keep hoping