Mac users insecure about security?

The question has been raised at
Forwarding Address: OS X, a weblog for and by people migrating to OS X,
and it is being debated in terms of the recent announcement by Symantec that due to increased market share OS X may soon become more of a target to virus writers and script kiddies.

Chris Cummer seems to think that Mac users were a little too quick in crying foul at Symantec. Perhaps Symantec wasn't just announcing this to increase its sales, but to make a new crop, and the old guard, of Mac users aware that their security through obscurity doesn't work when your operating system isn't as obscure.

I know that OS X is inherently more secure than Windows, but that doesn't make it bullet proof. It only makes sense that as the Mac's share of the market increases more and more people will start o write malicious code to try and infect all those shiny Apple boxes out there. 

What do you think? Is Symantec just trying to get some money from worried Mac users, or is the threat real?