The basic G3 design remains the same since the first Sawtooth. You can see it in Apple's developer documents. The whole motherboard stays the same save for a faster Ethernet chip, the rest of it changed nothing. The multiple CPU support is only behind the memory bus. They used the same old north bridge, same old PC-100 memory.
Nothing is new.
And it's very inefficient for a dual model. If a PC motherboard maker does the same, it will be nuked by angry buyers in a week. Apple has given up the hope months ago. In fact, I believe it was long ago. When they decided to take the Altivec approach, they knew this instant boost could be the last bonus to take.