Thinkpad T23 is the canonical Plan 9 laptop. Everything I've tried on it works: apm, sound, wifi. The Actiontec 800MIP (branded WaveLAN) wifi card it ships with actually works.
Thinkpad T42 is likewise well supported. The wifi card(s) it shipped with did not work for me, but its Mini PCI slot is compatible with the Actiontec 800MIP from the T23. Note: replacing the wifi card requires completely disassembling the laptop. Many screws. Another option for wifi is PCMCIA, which has the benefit of being available on almost all laptops. However, I've not had great luck. The WaveLAN PC24E-H-FC works, but exhibits abysmal performance. Other WaveLAN PCMCIA cards I've tried have not worked at all. I'm not certain if this owes to incompatibility or faulty hardware. It's also possible that support for the specific PCMCIA controllers in my various laptops is buggy. -sl
