iOS 5.1 Safari bug
Bad bad bad
Pull out your iDevice running iOS 5.1 and navigate to this link with mobile safari http://arronhunt.com/facebook/ (must be on an iOS device running 5.1) Click the "connect with facebook" button. When facebook opens, attempt to login. You'll see what happens.
Pretty bad bug if you ask me. Definitely opens the gates for extremely easy phishing attacks. It allows you to hijack the URL and title of a new window and make it become whatever you'd like. In my example I used facebook. I would then create a facebook login mimicker and wait for people to input their credentials. I could then store credentials, forward them to the real mobile facebook and they wouldn't know anything happened.