"This is the first time we have come across a mobile phone virus that has two spreading mechanisms," says Mikko Hyppönen, director of antivirus research at F-Secure.Lasco.A infects mobile phones running Symbian OS with Nokia's Series 60 interface. The virus will copy itself inside all SIS (Symbian Installation System) files and when users click on the SIS file it will install the virus on their mobile phone.
Currently it's only a proof-of-concept virus - it has not yet been found in the wild but that could change soon.
More info at PC World