Apple Thoughts: Safety Tip: Disable AutoFill in Safari to Avoid Exploit

"Websites can now steal your Safari browser autofill information including Name, Address, Email, Credit Card etc. without a mention using a very simple exploit detailed by Jeremiah Grossman."

Malicious web sites could get personal information from your Address Book if you leave AutoFill on, so this is a pretty simple fix until the situation is addressed by Apple. According to Jeremiah Grossman, Apple has been notified but no word yet on a fix, well other than turning it off.