On ubuntu karmic, I uninstalled network-manager and tried to configure my Thinkpad T41p's ar5212 wireless connection manually.
iwconfig wlan0 essid MyEssid
iwconfig wlan0 txpower auto
When I run iwconfig, it says "not associated" and doesn't appear to be looking for an AP. It'll stay like this forever.
But if I run dhclient wlan0, within a few seconds it'll associate and get an address as expected.