Security issues with smartphones

These days you can see almost every other person (atleast in corporate world) having a smartphone – a blackberry or a symbian/windows mobile phone, which not only lets you make and recieve calls but also provides internet connectivity enabling you to check emails, access calendar and surf internet on the move.  Since so many people are carrying these devices (including me) that are connected to internet all time, I wonder how many of them have anything like an antivirus or some sort of firewall installed on their phones. I think this is a very serious issue specially after reading this article -

http://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9014118 

Whenever I (and I think alot of other people) have bought a new computer or reinstalled OS on a computer, first thing I do is get all latest patches, install virus scanner and configure a firewall. I really wonder how many people update their smartphones with latest patches. Also I never connect my computer to internet directly without a router being in between or a firewall being installed on it but our smartphones dont have any kind of firewall and are connected to internet all the time.

I think this is a very important security issue specially for corporations whose employees have these phones and might have alot of confidential information/data stored on them.