FWIW, the wifi on my PC900 netbook stopped working after I upgraded my ASUS PC900 netbook to Ubuntu 11.10. It had worked fine with Ubuntu 10.04/10.10 and 11.04.

My WiFi connection was provided by a portable "MiFi" battery-powered/USB pod-stroke-dongle, so I thought that if the problem was the wifi stuff, perhaps I could plug the dongle in directly via USB and get a net connection that way (worked on 10.xx, and probably also 11.04).

Big mistake. Not only did Ubuntu's networking not see the dongle, it changed something on the dongle's internal settings or filesystem, so that when I then unplugged the dongle and plugged it directly into a machine running XP, that machine immediately crashed, and refused to reboot while the dongle was plugged in.

So now I don't trust 11.10 enough to plug any other hardware into it.

(BTW, I don't personally need a solution to this, because there's no important data on the netbook, and I'll shortly be wiping it and reinstalling good old 10.10. I just thought I'd give 11.10 a quick go to see what was new.)