Hi Guys,
I'm in the same boat (updated iphone 4 to iOS 5.0.1 and started having WiFi connectivity issues in my house). I finally got fed up and scheduled a Genius Bar appointment at the local Apple Store (tip: download the apple store app and schedule the appoint through it and save time). Meanwhile i changed my access points' channel to 11, 2 weeks ago, from the default which was "optimal". Now I am able to stay on WiFi reliably at home.
I note though that this week I went into a different apple store to find out what my options were for a repair/replacement. I pulled out my phone and the greeter got to see the infamous spinning wheel while the phone looked for WiFi connections that never ends. His comment was, "that shouldn't happen."
I also note that for some reason, my phone is now able to find wifi connections in my house by switching to airplane mode for maybe 1 minute, then switching out. I've not connected my iphone to itunes in over 1 month. In front of the apple store greeter, I tried the airplane mode trick and it worked. Until I switched my access points to channel 11, nothing I did would get the phone to see the WiFi, short of rebooting.
Best,
jeff