There definately is a bug in the WiFi-implementation in OSX 10.7.3.
My Mac mini with Atheros 9280 AirPort-card that was working without any problems in OSX 10.7.2 and even had the AirDrop-option, gave a "WiFi: no hardware installed" error after upgrading to 10.7.3...
I've spent a lot of time trying to get things right and did try all options supplied everywhere (repairing permissions, zapping PRAM, replacing the .kext from TimeMachine, manually reinstalling the 10.7.3 Combo update, etc. etc.)
nothing helped... or other options (like reinstalling OSX or downgrading & upgrading OSX) seemed to work properly on first installment, but got me back into the same error after the first restart of my Mac (and after every restart ever since)
...until I noticed that one thing was really odd : when starting up in 'Rescue Mode' (pressing Apple(CMD)+R during startup) I noticed that then my WiFi was 'magically ressurected' ; the AirPort-card was recognised and automatically reconnected to my AirPort/WiFi-network...
I've found only one way to fix this :
1- download the Kext Utility here : http://cvad-mac.narod2.ru/Kext_Utility
2- then… reinstall the IO8211Family.kext from 10.6 Snow Leopard and reboot (get it from a 10.6 install DVD)
3- and only after that... you will be able to successfully reinstall the IO8211Family.kext from 10.7.2 (get it from your TimeMachine backup) [this last step is only needed if you want the AirDrop-option back]
The odd thing is that the IO8211Family.kext from 10.7.2 seems to be exactly the same as the one from 10.7.3 since they have exactly the same version number (4.1.2) and creation and modification dates...
...and directly installing the IO8211Family.kext from 10.7.2 onto 10.7.3 doesn't work either...
The only difference I've noticed is that the firmware is now “Atheros 9280: 4.0.61.4-P2P” under OSX 10.7.3
but it used to be “Atehros 9280: 4.0.58.4-P2P” under OSX 10.7.2...
That could be the source of this problem…
Could it be that the 10.7.3-installer updated the Atheros 9280′s firmware, but that 10.7.3 itself isn’t compatible with the new firmware ???
Please Apple - get this fixed a.s.a.p. - it's not acceptable that there is a "WiFi: no hardware installed" error on Mac with a fully functioning original AirPort-card...