Beware for all iPhone user that using jailbroken phone, currently the 1st iPhone worm is discovered in Australia. The worm will change the wallpaper to an image of 1980s pop crooner Rick Astley. The worm is capable of breaking into jailbroken iPhones if their owners have not changed the default password after installing SSH. Once in place, the worm appears to attempt to find other iPhones on the mobile phone network that are similarly vulnerable, and installs itself again.

If you have jailbroken your phone but you did not install the SSH then you are safe, but if you do install SSH what you need to do is frequently change the SSH root password.

via sophos.com