Such cybercrime is worth big money, whether it happens on your PC or smartphone. Cybercrime in 2011 cost consumers $110 billion worldwide and $21 billion in the United States, according to Symantec's recently released (PDF).

But online crime may soon cost us more. The frequency of mobile threats doubled between 2010 and 2011, Symantec says, and 35 percent of online adults worldwide have either lost or had their mobile device stolen, exposing them to identity and data theft.

In its report, Symantec defines mobile cybercrime as unsolicited text messages that captured personal details, an infected phone that sent out an SMS message resulting in excess charges (typically known as toll fraud), and traditional cybercrime such as e-mail phishing scams.

It sounds like your cell phone is open to some nasty threats, but is mobile security really something you should be worrying about? Does your smartphone need the same kind of 24/7 threat detection that your PC does?

No doubt, mobile devices are the next big target for malicious actors looking to make a quick buck. During this year's , for example, vulnerabilities were demonstrated against popular technologies used in mobile devices such as near field communication, baseband firmware, and HTML 5.