Does the WiFi on your iPhone 3G work every now and then, or not at all?
If it works every now and then, when does it stop working? Is it after a (long) while surfing on the net with the WiFi, or not?
Have you noticed if the back of your iPhone was unusually hot when the WiFi problem occurs?
Is your iPhone 3G one of the first ones or one of the last ones to have been built?
There have been problems with the WiFi of the first 3G series, which were believed to be related to an excessive heat produced by intensive use. Some have tried putting their iPhone i the freezer, but I wouldn't advise you to do so.
I don't know if this might be relevant to your iPhone.
Have you tried restoring your iPhone (and why not upgrading it to iOS 4).
I'd also like to know any possible to fix the wifi on iPhone3G.
I lose my wifi function 1 week ago - after a heavy used(long surfing), it just cannot detect any access point.
I have upgraded to iOS4, but the wifi still not working.
Your suggestions are appreciated.