Reboot does not solve this issue permanently. As soon as sleep is induced your airport is gone again at wake-up.All is not right in Security Update 2007-004 land. My Panther 800mz G3 iBook will connect to the internet on initial boot. However, after wake up from sleep the Airport cannot find local wireless network. Reboot solves issue, but what a pain. Is next fix at least a month away?
That seems to be exactly the problem most are having if they run 10.3. Which I do on a few older (2003) machines. But I seems to be OS related as even g4 powerbook users are having the same problem. I would look for a TON of posts about this as people run the update this weekend.