The "Cabir" worm infects phones running the Symbian mobile phone operating system, and although not seemingly found in the field yet, the day of the mobile phone virus could be upon us sooner than we thought.

"Cabir spreads between mobile phones using a specially formatted Symbian operating system distribution (or SIS) file disguised as a security management utility. When the infected file is launched, the mobile phone's screen displays the word "Caribe" and the worm modifies the Symbian operating system so that Cabir is started each time the phone is turned on."

More here.