The Radio Popper P1 is a new radio based flash synch system which offers high speed remote flash triggering via radio even without line of sight. It’s very nice technology, but what makes it special is the price, which is way below comparable systems. They’re only taking pre-orders for the US at the moment at a price of $180 for the transmitter unit and $180 for the receivers (Canon and Nikon only). Here’s a nice demo video to watch.
The RadioPopper P1 system forms a radio based “bridge” between Master and Slave flash units ordinarily operating by a “line of sight” infrared triggering system. The P1 system when combined with your existing Master / Slave wireless flash units effectively gives you the world’s first true eTTL / iTTL by radio, the world’s first high speed sync by radio, and all in a very compact and light weight unit! Every feature you love about your existing “line of sight” wireless triggering system without the limitations imposed by that line of sight.
You also need a Canon or Nikon dSLR that has wireless lighting control built-in or a wireless commander unit.