CMP trade publication Information Week ran an article today on a recently published paper which argues that web browsers should have an expiration date, just like perishable food.

The recommendation is based upon an estimate in the study that found over 45 percent of the internet population is using out-of-date browser software, leaving these users vulnerable to all kinds of known security threats.

The paper's authors make a provocative claim about the relative safety of different browsers:
Firefox 2 is considered to be the most secure Web browser because 83.3% of its users worldwide are running the most current version. Second, third, and fourth places go to Apple Safari 3 (65.3% of users running the most current version), Opera 9 (56.1%), and Microsoft (NSDQ: MSFT) Internet Explorer 7 (47.6%).

 "It is noteworthy that it has taken 19 months since the initial general availability of IE7 (public release October 2006) to reach 52.5% proliferation amongst users that navigate the Internet with Microsoft's Web browser," the paper says. "Meanwhile, 92.2% of Firefox users have migrated to FF2."
The reason this claim is prone to controversy is because one could make the plausible argument that the latest-and-greatest browsers aren't necessarily bug free. It's more likely that they, too, have security holes.  The only difference is that their security holes are still yet to be uncovered. Regardless of which side you fall on the never ending browser war, do yourself a favor by keeping your browser up-to-date. 

As someone who is responsible for developing a hosted blog software service that must work on several different browsers, I'll confess to having an ulterior motive for encouraging this.  Migration away from older browsers, like IE 6, reduces the need for web standard non-compliances workarounds, making the task of coding web pages a much simpler one.