I'm in Japan and have a Softbank iPhone 4 and I have the oppiste issue of sorts. My wireless connection has gotten better but I have lost my home WiFi. The iPhone can't even find the networks I have set up or even if I'm right next to the router. I can pick up other WiFi's but I can't pick up my Netgear system. I have tried all but doing a RESTORE to the iPhone. I'm not looking foward to doing that and then have to wait to get everything back up again. Apple Needs to get this fixed.
I also have 2 iPhone 4's from the states and after the update, I have had the same issue with the wireless. I never had an issue before the update, but right after words it quite working. The only system that was unaffected was my WiFi iPad. This went flawlessly to hook the iPad up and it is still working. It just seems to affect the iPhone 4's from Japan and the US.
Any Ideas? Apple are you listening, this needs fixed ASAP, don't be like "BlackBerry RIM" and now start having problems....