I always love to read about F-Secure posting on mobile security. Yesterday they have found out that SymbOS/Cardtrap.A will copy 2 windows worms to the infected phone's memory card. Once the user connect memory card to the pc, the autostart function (if supported by your windows) will actually attempt to start the 2 worms in the card.

From F-Secure weblog,

SymbOS/Cardtrap.A is otherwise unremarkable Symbian trojan, except that it also tries to infect users PC if user inserts the phone memory card to PC.

When infecting Symbian phone the Cardtrap.A copies two Windows worms Win32/Padobot.Z and Win32/Rays into the phones memory card. The Padobot.Z is copied with autostart.inf file in attempt to start automatically if the card is inserted to PC using windows. The Rays is copied with filename System and same icon as system folder, this is done as social engineering attempt so that user would click on Rays instead of System folder.

http://www.f-secure.com/weblog/