Wi-Fi connectivity problems are not limited to the iPhone 3GS, not by a long shot. The iPhone 3G is widely reported to have connectivity problems that, according to the large number of people discussing it on the Apple Support Discussions, dwarf the reports regarding the 3GS.
In over fourteen Apple Discussion threads, over six hundred messages have been posted with the first one being written on June 17th, shortly after the release of iPhone 3.0 software. These threads have been read by thousands of users. Unfortunately, to date, a solution is not at hand.
The problem, verified by many, is that when updating to the new software, Wi-Fi connectivity on the iPhone 3G either decreased or vanished entirely. Those who were used to getting full bars of Wi-Fi connectivity now experience markedly less bars. Worse, even if some signal strength bars are displayed, often there is no Internet connectivity.
Many solutions have been proposed including resetting the router, changing settings (seemingly at random), and even putting the 3G in the freezer:
"Also i might note, I turned off wifi, turned off the phone, put it in the freezer (in a bag) for 10 mins, turned the phone back on, put the phone right next to my wifi antenna and then turned on wifi and it joined, it JUST joined and I couldnt believe it," says one forum poster. Several others report similar results, but this fix did not last long. In fact, blog posts have been written about possible solutions, but none of them seemed to pan out after using Wi-Fi for a short period of time.
Some writers have said that the 3.1 update will fix the problem while a larger number say that the new software release won't help at all. To prove that this is not an isolated incident, one user wrote about upgrading four iPhones and experiencing the problem on every one of them.
Replacement iPhones have been circulated through Apple Stores, but that didn't seem to fix the problem either. This brings up a a hardship that we in the US, with available Apple Stores, don't have to deal with. In some countries, like Italy and Croatia, all repairs are done via mail order with a four-week wait. The quandary becomes whether to send in your phone and wait a month with no guarantee of a fix, or to wait for the 3.1 software revision which again, may not solve the problem. What to do?
A lesser but salient problem reported in the Discussions is a lack of Bluetooth connectivity in conjunction with the lack of Wi-Fi. It seems that losing Bluetooth for those affected is a package deal with Wi-Fi since I haven't found reports of Bluetooth vanishing by itself.
Apple is reported to be well aware of this problem. As time goes on and the number affected increases, Apple Stores are acknowledging the problem and replacing phones, but to no avail.
If you would like to delve deeper, here are a number of Apple Support Discussion links discussing this problem.
Using the old saw of 'a squeaky wheel gets the most grease,' perhaps a preponderance of evidence will get Apple moving on such a widespread malady.
If you have experienced this issue, please comment about it.
Thanks to everyone who sent this in.