Hi,
No help for you I'm afraid, but I have the same issue.
Loss of WiFi, from reading around (yes, I'm a forum ho') seems to be related to loss of the wireless address....
Mine was on the blink in any case(sometimes on, sometimes off), and I had reset the network settings.
I updated to 3.1.2 and wifi is no longer an Iphone option!!
Phone can't find the network supplier either half the time and has to be rebooted. Its not a phone - its a PC (yes, like 'PC' in the ads
unreliable)
Permanently greyed out.
I Followed the tips in support.apple.com/kb/TS1559 Unable to use Wi-Fi or Bluetooth with iPhone or iPod touch because there's no address listed for the device - you may want to try.
No luck for me!!
Called my supplier - who basically just refer you to the above articel, sigh.
They have said that that process performs a complete software reset and so it must be a HW problem. Have to take it back under warranty.
I reckon he may be right.
Hmmm - Buying apple used to mean 'it just works' - welcome to land of mass production....