I have an iPhone 4 iOS 6.0.1 and my Facebook and twitter does not work. With Facebook I can't get passed the login screen it just shuts off and twitter I can log in, scroll a bit but that's it.
I have restored my phone to a fresh 6.0.1, still not working I downgraded to 5.1.1 and both apps work perfectly fine. It worked when I first got iOS 6.
I was just about to say I don't know how this could have happened. But I remember downloading a load of apps and 18 updates were available (so many updates cos my phone was been mended so I missed out on 6.0 and went straight to 6.0.1) but after I downloaded all of them, later that day a Facebook update was available. Maybe the update is the problem. I don't have a solution as of yet safari browser will have to do for you guys until another update. But id downgrade to 5.1.1 if you have the shsh blobs. ill reply if I find out anything
Nathan