As observed by Dan, The Register reports a bug in the Motorola RAZR:
A bug in Motorola’s RAZR firmware could allow a malformed JPG file sent over MMS to overflow the stack, theoretically making it able to execute arbitrary code.
… and do what, precisely? 😉
So you can execute arbitrary code and, I dunno, maybe do a naughty calculation. Like spell out BOOBLESS on the display (80087355)?
Or take you to a particularly naughty mobile web site that doesn’t display properly at all? Next. Dinny worry.