So, two interesting pieces of news from the Poulsbo front.
First, hopeful indications on the driver development front. Phoronix presents it fairly negatively, but the key thing here is that Intel guys are actively working on providing the driver in a form that's generally usable: that's clear from the discussion. Reading between the lines, they seem to be planning to provide the existing messy and partly closed source driver in a form that will be usable on something beyond just Ubuntu 8.04 in the short term, and in the long term, rewrite the driver so that it's fully open source.
Secondly, thanks to a hot tip in the comments to my original post, I've actually got native resolution display on my Vaio P now. That's the good news. The bad news is that it's still slow, and somewhat tricky to configure.
Forget about uvesafb and all that crap. Adam Jackson has the goods, as usual. He poked me on IRC and asked me why I hadn't just figured out why the plain vesa driver wasn't given native resolution, which was a good question that I didn't have a good answer for - should've been the first thing I did when I booted it. It turns out to be a classic issue: DDC/EDID probe of the monitor fails, so it falls back on default vertical/horizontal refresh range values which are too low for the native resolution (1600x768) to be considered valid. Probably you could fix this just by the good old-skool method of hand-coding the appropriate values into the xorg.conf file. However, for Fedora users, it's even easier: there's an updated package (xorg-x11-drv-vesa-2.2.0-3.fc10) coming to Fedora 10 updates soon. That has a fix which gets the panel size by a different method when DDC probe fails, and that solves the problem on the P. So with that package installed, the P will give native resolution with the vesa driver, no messing about.
Thanks to Adam!