Looking at the return response-to-request flashes it appears the explanation Max gives makes the most sense, that a group, regardless of number of members have all the same power command based on the simple agrigate of light reflected by the subject. If one flash is pointed in a direction that does not contribute to the agrigate of the return pulses, the power is set for all remotes in the group to the same power, at a level based on the light that was actually returned. It does not make any difference to the commander where the flashes are pointed, just to amount of total reflected in determining the power level. This part of the equation is simpler than most posters want to make it. There really is enough information to use in some useful accessories like RF links. I am going to California for 3 weeks and if I have room to bring an Arb Waveform Generator back, I will. That would be fun programming a simpl lighting controller using a laptop. Next would be reducing it to an embedded processor, maybe a PIC to keep it simple. My own RF wireless TR/RX is really simple, it does not know what the pulses mean, just picks them up inductively, shapes them and sends them using 2.4Ghz RF link. The pre-flashes operate as normally. It would be nice to build in the RF links directly into the flash units and commander. I have not taken my SB900 apart to see how much room there was for an RF module. I have taken my Sigma 530Super apart to see how it is made and I think there is room inside for the receiver.
I designed some custom designed audio transmitters and receivers we have made for us and imported from China. We sell to guides and tour companies, and rent them by the thousands every day in the summer. They are used for guides to talk to their tour group members who wear matching receivers. Those operated on channelized frequencies in the 730Mhz range, and are too large to fit inside a flash for sure but it would be fun playing with those transmitters because they have a great range, about 1000 meters if in the clear. My little surface mount MMC 2.4Ghz are pretty limited in range, maybe 75 meters. For someone doing landscape work having a great operating range might be useful. If I owned stock in PW I might be worried now;>) There is no technical or manufacturing reason for even their cheapest units to cost $175 each.
The idea of building useful accessories always intrigues me and I might suggest a DIY forum topic for sharing plans or suggestions. Everyone has an idea for some light modifier or attachment system. Who would I suggest that to in Nikonians for consideration? Stan St Petersburg Russia