Now that I've had it for a bit and am mostly using it as my primary laptop, here's a little detail on how well it works with Debian. It's not perfect (see below), but it does let me get work done.
Wifi is the big problem. The latest vendor driver doesn't seem to be able to stay connected to the network for more than fifteen minutes or so with any kernel I've tried building it against. There's a previous version of the driver linked off an ubuntu bug that seems to work acceptably with the 2.6.30 kernel that was in squeeze until last week (and still appears to be in lenny-backports). Unfortunately, it seems to exhibit similar behavior to the latest driver when built against the 2.6.32-trunk that's now in squeeze, which is annoying because...
Sound almost works. It plays things just fine over the speakers; it just doesn't turn off the speakers when you plug something into the headphone jack. Some digging suggests that this is because the snd-hda-intel driver doesn't know specifically about the codec/mixer mixer and is making guesses that turn out to be wrong. 2.6.32 appears to know about it, but I haven't checked that it fixes the headphone problem because I care much more about wireless support.
X, on the other hand, worked more or less out of the box, although it seems to be happiest (2D-acceleration-wise) when beaten into using the radeonhd driver. Really, I was so flabbergasted by getting a working xterm using the full resolution of the display when I started the server with no xorg.conf that I forgave the ati driver's usual detection problems.
Suspend-to-RAM via pm-suspend just works.
I suspect that the problems will get sorted out over time; the Realtek 8192 seems to be moderately popular, and having a working in-kernel driver would likely make all the pain go away. Still, a couple of weeks on, I could only be slightly more pleased with this computer.

Well, the X100e has an Athlon Neo MV-40, and I believe AMD bought ATI a while back... but what do you want for $450?
With the latest squeeze version, 2.6.32 kernel and the realtek driver (v15), the wifi is rock solid on my x100e. I still haven not managed to get the ati drivers to work however.