Apparently there is a new anti-phishing feature in the new iPhone 3.1 software which alerts the user when they happen to visit fraudulent websites states an article over on quickpwn.

Phishing, for those that aren’t in the know, is a website that is disguised as another website and then steals the user’s log-in info once entered. The anti-phishing feature in iPhone 3.1 is set to on by default, and to check to make sure it is you can go to Settings — Safari, and then slide the “Fraud Warning” button to on.

Apparently the new anti-phishing feature works really well and alerts you when your iPhone hits a deceiving website so you can leave immediately.