Infecting a mobile - is it tougher?

Why haven't smartphones like the Nokia N97 or N95 been overrun by a avalanche of worms and viruses like PCs have ? According to researchers at NorthEastern University, in Boston, these phones have been safe because no single cell phone operating system has achieved a big enough market share for a major virus outbreak to occur.

But with the way Symbian S60 smartphones fly of the shelves that could change pretty soon. Anonymous call data from 6.2 million mobile phone subscribers have been used to simulate the epidemiology of a virus outbreak. Like flu and SARS, bluetooth viruses spread slowly, through close physical proximity(bluetooth range). On the other hand, viruses embedded in multimedia messages such as tantalizing picture messages spread much more rapidly but are usually confined to groups of connected people(colleagues, friends) who share the same kind of phone. Problem is, with Bluetooth 3.0 coming about, things could get mighty messy.