Originally posted by BretW This is cool, but given that it is possible, why is it not being used by camera manufacturers?
Camera manufacturers have been getting away with just supporting optical triggering. It works in general, but starts to get problematic in bright sunlight and you always need line of sight which can be a great limitation.
A number of third-party flashes have been released/announced that have built-in radio triggers. With the latest generation of triggers (e.g., from Yongnuo or Cactus) you will be able to remote control the power settings and of course trigger the flashes.
For other brands similar systems have been available for a while (e.g., the Phottix Odin) and those even support i-TTL / E-TTL, but they needed extra receivers for the flashes and weren't exactly cheap.
Many "strobists" don't want P-TTL but swear by manual flash control. I'm in that camp as well. I've been OK with walking up to my flashes and change the power as needed, but now cannot wait to see the release of triggers that allow remote control of the power settings.