OS X is a unix based system. Go look up the market share of servers between Windows and unix/linux. Obscurity helps, but it is not the sole reason. The fact is that there is not 1 single self propagating virus in the wild for OS X.
Nathan, it's market share and nothing else. Look around, it's a Windows dominated universe with Mac's occupying the same niche market they've always had. And it's the same whether it's in the corporate world or home use, Windows is everywhere.
Personally I'd like to strangle the sumbeech who came up with the VI editor.
