Hhm, I guess with the growing importance of the OSX platform this should be a number 1 item. Especially now, when many new people join the parade.
The last thing I would like to see is that people get sloppy applying regular fixes and some of the vulnerabilities become actively exploited.
I suppose so, but in reality you could probably be running an unmodified 10.2 box on the internet and statistically the chances of a vulnerability exploiting your machine are probably about the same as the latest Leopard machine with all security updates.
You can never, ever be blasé about security, but the Mac has never had a history of being the victim of real world exploits like other platforms.
Market share is only one part of the picture, probably smaller than many people like to make out, having more join the parade won't necessarily make the Mac more or less likely to be exploited.