Holly Webber recently asked Vanja Svajcer, a principal researcher at SophosLabs, about the challenges mobile devices present (emphasis mine):
The new devices of course need to be secured, especially as people use
their own private devices. But what they bring in is a complexity in
terms of the numbers of platforms that suddenly the internal IT people
have to support. Some of the platforms, such as Blackberry and iOS, have
shown to be relatively well protected or isolated. For Android, it’s a
completely different story. Android is more open, and it’s similar to
what Windows used to be 10 years ago. You are allowed to install
applications from all sorts of websites, and the malware writers have
seen this and started writing malicious code for Android smartphones and
for tablets. I think now we have about 100,000 unique pieces of malware
for Android in our collection.
Open always wins.