only thing that bugs me is that i just bought the SB800. but you can never have too many speed lights and with the 900 having a phyiscal switch to go back and forth for the wireless mode, i can keep the 800 in wireless.
$500 is kinda crazy for a flash in my opinion. I do want it, a probably will buy it very soon though. I need another flash, but I was looking at another 800. This guy is $200 more! It does have some really cool features though, and is rumored to be easier to use than the 800.