While reading that Rich Mogull has joined TidBITS (Congratulations, Rich!) as its security editor, I noticed this point in the announcement:

Although Mac OS X has proven quite secure, that’s not happenstance, and is largely due to frequent security updates from Apple.

This is the first time I’ve seen someone suggest that a higher number of vulnerabilities followed by security updates makes a platform more secure. I would be surprised to find out this is a common line of reasoning in the MAC community.

In any case, it certainly aligns itself better with the evidence. While I sympathize with this thought process, I suspect that less frequent security updates could support the same notion.