| The live view most likely requires a second CCD, up in the prism; added cost may keep that feature in only the high end SLRs. After 2 or 3 more generations though, competition may make them include that in all.
Interesting in the 580 EX II description: "A new Off-Camera Shoe Cord, Compact Battery Pack and Speedlite Bracket (also released today)" ...the off-camera shoe cord is one accessory I've been meaning to get. I wonder what's changed. | 
