I have this issue as well but only for certain wireless networks. Everything was working fine at work where I updated both my devices, but as soon as I got home and tried to connect to my Time Machine's wireless network, I can't connect.
The odd thing is, I keep having a login screen, like the kind that pop up when you have to login at a place like starbucks, that tries to go to a page on apple.com. No idea why it is bringing this login sceen up as it shouldn't be needed in order to connect to my home network. This is happening with both my iPad 2 and iPhone 4.
I've tried all the steps short of reverting to a backup/ios 5