So, an update on the Vaio P and Linux.
Basically, it works, with one big caveat. I had some fun getting it to install Fedora 10 - the live CD ISO to USB converter script just didn't seem to work right, whatever I generated would boot to a flashing cursor (on any system, not just the Vaio). Finally I found something that worked - using Unetbootin to set up a Fedora 10 network install. (Using it to set up a boot of the live CD image didn't seem to work). Once I found that trick, install proceeded perfectly normally, but in text mode - a shade of things to come.
The system booted to text mode. /var/log/Xorg.0.log showed it trying the intel driver, failing, then trying fbdev and vesa, and falling over on fbdev. So I stuck in a basic /etc/X11/xorg.conf to force it to go straight to vesa rather than try fbdev, and that works. Bottom line: this system uses the new Intel GMA 500 graphics chipset, which is not actually a successor to previous Intel chips at all, it's a completely foreign architecture. It's a PowerVR chip, more or less, and there is not yet any native driver for it. I'm fairly sure this is being worked on and there will be one reasonably soon, but for now, VESA is all you're going to get. Which means it's slow and won't drive the display's (ridiculously high) native resolution. I can live with that, but it's nowhere near optimal. I hope the native driver shows up soon. Note that if I'd run the installation with the 'vesa' kernel parameter, it would probably have worked in graphical mode and set up the VESA driver out of the box too, so if you're installing on a P, probably best do that.
Mandriva will likely do 'the right thing' out of the box - graphical install will work, and it'll use the VESA driver.
Wireless is an Atheros chipset, which appears to more or less work out of the box with the very new 'ath9k' driver. I haven't tested whether the sound actually works yet, but it's Intel HDA and the driver is loaded, so even if it doesn't it'll just be a case of a quirk to be added upstream, so either it works or it will soon.
Haven't tested the Bluetooth yet but it shows up without errors, so I expect it'll work.
Suspend basically works, but the display part doesn't. The system itself suspends and wakes up again, but the screen backlight doesn't wake up. If I tilt the display so I'm looking at it from the bottom at about 120 degrees, I can just about make out the console. I suspect that may well be fixed with the native display driver, when it shows up. The basic kernel support, though, is clearly there, so I expect this to work in future.
The webcam works out of the box with the uvcvideo module. Cheese works just fine. Bit slow with VESA as the display driver, though.
So my overall take is the Linux support for this system isn't quite all there yet, but it likely will be quite soon. Overall, my first impressions with the unit are very positive - the weight is ridiculous, it's just a massive gulf to the weight of a regular netbook. The screen's amazing, the build quality of the unit feels very solid in good-Sony style, the keyboard's great, the 'mouse' is decently implemented. We'll see how it fares over time.