I use a sony z-series (z590) laptop. It's a 13.3" display, 1600x900 resolution, core2 duo@2.4 GHz, 4GB RAM, and it gets 7.5+ hours of battery life (with wifi enabled; ~9 without). If your eyes don't like tiny fonts it's not for you, and I had to do some unholy stuff to enable the virtualization because sony are bastards, but other than that, I love the thing. It's a carbon-fiber frame, and it weighs almost nothing.
EDIT: also, I'm running Gentoo on the thing. Everything works well except for the nVidia chip (which I don't like anyhow), the integrated camera (which sort of makes me sad), and as far as I know, the Sprint 3G network adaptor. I don't actually know that the 3G adaptor doesn't work, and I've seen claims that it does, but I've never tested it myself.
I followed the directions at http://feature-enable.blogspot.com/ , and it worked out perfectly. You basically put a modified copy of grub in a certain directory structure on a USB key and reboot your laptop. The laptop's EFI firmware (normally hidden by a BIOS emulator) sees the modified grub and loads it instead of the BIOS. Then you get to poke some flash values, and reboot. It's a little scary, but I haven't heard of anybody breaking their laptops from it. It worked for me.
EDIT: also, I'm running Gentoo on the thing. Everything works well except for the nVidia chip (which I don't like anyhow), the integrated camera (which sort of makes me sad), and as far as I know, the Sprint 3G network adaptor. I don't actually know that the 3G adaptor doesn't work, and I've seen claims that it does, but I've never tested it myself.