After installing Ubuntu 8.04 on my T60, I was supprised that wifi network card does not work at all.
After searching and googling I found next: In the kernel 2.6.24 driver for Intel PRO/Wireless Card 3945ABG was replaced from ipw3945 to iwl3945, and because of some bugs it does not work by default.
Google has a lot of suggestions about this issue, and after two days probing each of them, workable solution was found. Workaround is :
1. sudo modprobe -r iwl3945
2. sudo modprobe iwl3945
3. create a file named iwl3945 in /etc/modprobe.d/