Hardware: Acer 8204WLMi laptop (specific issue with Intel PRO/Wireless 3945ABG wireless LAN).
Previously had Ubuntu 8.04LTS installed and updated to 18 Feb 2009. All hardware worked out of the box with 8.04LTS. Used upgrade feature in Update Manager to move to 8.10 on 19 Feb 2009. Wireless no longer functional. The WLAN switch on the front of the laptop appears to be disabled (no light/no "enable wireless' capability with NetworkManager Applet 0.7.0). I ran lshw -C network indicating Wireless interface is DISABLED using driver=iwl3945 (results below with my MAC addresses "X"ed out):
dave@dave-laptop:~$ lshw -C network
WARNING: you should run this program as super-user.
*-network
description: Ethernet interface
product: 82573E Gigabit Ethernet Controller (Copper)
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:03:00.0
logical name: eth0
version: 03
serial: xx:xx:xx:xx:xx:xx
width: 32 bits
clock: 33MHz
capabilities: bus_master cap_list ethernet physical
configuration: broadcast=yes driver=e1000e driverversion=0.3.3.3-k6 firmware=3.1-11 ip=192.168.1.101 latency=0 module=e1000e multicast=yes
*-network DISABLED
description: Wireless interface
product: PRO/Wireless 3945ABG [Golan] Network Connection
vendor: Intel Corporation
physical id: 0
bus info: pci@0000:05:00.0
logical name: wmaster0
version: 02
serial: xx:xx:xx:xx:xx:xx
width: 32 bits
clock: 33MHz
capabilities: cap_list logical ethernet physical wireless
configuration: broadcast=yes driver=iwl3945 latency=0 module=iwl3945 multicast=yes wireless=IEEE 802.11abg
*-network DISABLED
description: Ethernet interface
physical id: 1
logical name: pan0
serial: xx:xx:xx:xx:xx:xx
capabilities: ethernet physical
configuration: broadcast=yes driver=bridge driverversion=2.3 firmware=N/A multicast=yes
Problem fixed. I don't know how it got fixed though! I made a Bootable USB flash drive with 8.10 and booted from the USB stick to see if I could get Wireless working with a Live USB. Sure enough, the Live USB had all the hardware working right off the bat. When I re-booted back to the hard drive on the laptop, the Wireless began to work without any configuration tinkering whatsoever! For whatever reason, booting off the Live USB seemed to kick the wireless system into life, so when I re-booted off the hard drive it was working right away. I don't know how this is possible, but that's what happened.