Canon Speedlite 430EX II vs. Canon Speedlite 580EX II

Good quick analysis of the two here

Personally, the PC connector on the 580 is the deal breaker.

Now that's a fast flash!

80 attoseconds (billionths of a billionth of a second) long. Wow. Link

Now if they can only get that into a speedlight (And a shutter that can handle it). :0)