There aren't that many out there, but there's a new Symbian worm in town.
Mobile phone viruses are few and far between. According to antivirus company F-Secure, what makes this Symbian worm different is that it attempts to propagate using common media file extensions, rather than standard SIS extensions like Commwarrior. Both pieces of malware still rely on social engineering to propagate.
From the F-Secure blog post:
"We have been working on an interesting Symbian worm over the last few days. It affects S60 2nd Edition phones.
The SymbOS/Beselo family of worms is very similar to Commwarrior. In fact at first we actually misidentified Beselo.A as Commwarrior.Y. Like Commwarrior, Beselo worms spread via MMS and Bluetooth using social engineering to trick users into installing an incoming SIS application installation file.
But what makes Beselo interesting is that instead of a standard SIS extension the Beselo family uses common media file extensions. This leads the recipient believe that he is receiving a picture or sound file instead of Symbian application. He is then far more likely to answer "yes" to any questions the phone prompts after clicking on such an incoming file.
The filenames used by Beselo are beauty.jpg, sex.mp3, and love.rm."
However, it's not clear what the worm does if users run the malicious file.
In my opinion, mobile phone malware is currently at an undeveloped stage, where users don't need to worry overly about getting infected - it would be a pain to be infected, but not catastrophic, and the likelihood of infection isn't high. However, you may decide that it is enough of a risk to get some mobile phone anti-malware software.