Just found the coolest wireless E-TTL solution.
Phottix Odin TTL
I got a set from the first shipment into New Zealand.
It's quite amazing, full E-TTL control including all of the functionality found on the back of the flash.
That means you can operate any E-TTL II flash (550ex, 580ex, 430ex) remotely as if it was sitting on top of the flash.
I've just been playing with it, and I'm pretty blown away.
It has an LCD screen and a very easy to understand control layout.
It's actually easier to adjust settings than it is on the flash.
With the flash off camera I was able to adjust the flash mode, power out put, flash Exp Comp, Zoom AND enable high speed sync.
It can operate groups, set ratios etc. The damn thing is awesome.
Way better than the Pocket Wizards Flex, or the new Radio Poppers.
The best thing is a transmitter and receiver combo cost less than a single Radio Popper or Flex unit.
I've used the Pocket Wizard Flex and found them to be rather fiddly and un-reliable, with limited control at best.
The Odin is liking have a flash on the camera, but with a better user interface.
I have no idea on how available they are globally, but here in NZ these guys stock them: www.photofans.co.nz