If you use the auto lock function were you have to place 4 passcode into the phone to unlock it, you can still access your favorite numbers,from there contact details, if you have emails associated to them, then your email accounts and emails are accessible and if any emails have website links, then they have access to safari etc

Best read it yourself, and watch the video demo of what can be done to prevent this until Apple release a fix

http://gizmodo.com/5042332/huge-iphone-sec...on-at-risk

Nick Former Mod/Member, with the most post & Chicken George Arch nemesis