I bought one of those U8240 a few weeks ago (thanks Google Summer of Code...)
It is an impressive device, without a doubt ; but I wouldn't say it fits the same category as the Zaurus.
It really isn't a pocketable device ; at least you won't feel confortable with it in any pocket.
However, it is well suited to be carried in a bag and used as a tiny and lightweight laptop.
The CPU is very impressive. You can play virtually any video without a glitch, even run most 3+ year old games. And since it's a x86 device, you have an unlimited supply of software. Otherwise, the wifi is quite good (except when used in tablet mode, probably because the antena is near the screen) ; I like the trackpoint a lot too.
However, what truly lacks is the instant suspend/resume feature, which rules out the title of Zaurus killer (beside the size).
Fortunately, I think the x86 familiy has made so much progress (size and power-consumption wise) that we might expect Z-footprint x86 devices soon.