http://opensource.co.uk/index.php/open-souce-news/213-the-smallest-threat-to-open-source-in-2009
His thesis is simple: that, because open source software usually lacks any mechanisms for easily updating to the latest security patched version, the growing popularity of open source software will render it more vulnerable to problems than its closed source counterparts.
As a lead-in to his main point, he said: