Apple has just released a special fix for iMacs that have WiFi-connection-problems each time they ‘fall asleep’, since the OSX 10.7.3 update (but… it’s a iMac-only fix…) :
http://support.apple.com/kb/DL1501
There is no accompanying info with it, so it is unknown if this update fixes the “no hardware installed”-error also…
…and is still remains unclear what the actual cause of this problem was…
MacManus.nl 
While I’ve not had dropped wifi signal since the patch went in, I HAVE had the wonderful realization that my page-load has slowed by 20-fold. I’ve had faster internet over dialup than I do, now.
Gimme the old, this isn’t “fixed”!
Thanks for your comment gyffes,
The “patch” you mean is the official fix by Apple – right ?
You are the first to notice any huge (or maybe even “any”) drop in internet-speed, I’ve heard of anywhere.
I’m interested if there’s anyone else having the same problem.