"This is almost certainly the year of the OS X exploit" (Feb 2006) http://www.securityfocus.com/news/113758
iPhone to be target of hackers (December 2007) http://www.networkworld.com/news/2007/121107-report-iphone-t...
Apple has a few extremely good security engineers (two of which were stolen from FreeBSD and whom I know personally). I've never believed OS X is bullet-proof, but it sure beats anything else I'd recommend to my 60+ year old mom. She's had more security problems with her garage than with her computer.
I taught a computer class to seniors in a community center a while ago ... I was horrified at the number of toolbars and browser plugins these people had managed to gather on their "mainstream" browsers/operating systems. My advice to them ... don't do online banking online!
I suppose a conceptually simpler security model isn't "magical" but in my experience it usually does improve the security of a system.
I am somewhat doubtful regarding a mac-bashing article in the "microsoft report" folder. But maybe that's just me...