Many of the Clevo Laptops (I've looked into the 12" ones) have Intel Wireless
cards, or come with a WiFi-card slot. That's not the perfect kind of free
software support if you ask me... Besides that, they seem to be really good.
Btw., you can't have coreboot on a laptop. One variant of the T60 Thinkpad is
listed by the coreboot project as somewhat compatible, but that's all. The
other ones are some extremely expensive high-end machines.
For now, the best solution in terms of freedom would be some motherboard that
supports coreboot, hopefully with an AMD CPU, and the GeForce 9500, the one
ThinkPenguin is selling right now.
As far laptops go, you are still stuck with the free BIOS/free graphics
dilemma: you can only have one of those things free, not both at the same
time in the same laptop...