Well, this hacker has quite the sense of humor.
Reports started spreading this weekend that iPhone users in Australia had been falling victim to "ikee," a worm that replaces default wallpaper with a picture of Rick Astley, the British pop singer whose song "Never Gonna Give You Up" has gained eternal infamy thanks to the mainstreaming of the "Rickrolling" prank craze.
Important note:
affects only jailbroken iPhones whose owners have installed SSH and neglected to change the default root password, ?alpine.?
http://www.wired.com/threatlevel/2009/11/iphone-worm/