I recently got a Buffalo wireless router, and since the switch, I can no longer see my wireless AP. If I run the iwlist wlan0 scanning command on the phone itself, I do not see the AP. However, if I run it on my linux laptop, this is what I see:
When I say upgraded it, I upgraded the firmware of the wireless router. If you follow the link, you'll notice that some other people have apparently tried a different kernel and reported that resolved the issue as well. Upgrading the phone appears to be a little more difficult since it is even less of a standard upgrade process (you have to manually download and install it, as opposed to using apt-get ...).