Bad news for Mac users: the first construction kit for Mac OS X Trojans has appeared. That comes just as Microsoft released a report showing that Windows 7 is far safer than previous versions of Windows. So while it's true that the Mac is still safer than a PC, the security difference between them has begun to shrink.

The Trojan construction kit for Mac OS X "is the first of its kind to hit the Mac OS platform," Peter Kruse, a partner and security specialist at the security firm CSIS, writes in his blog.

Why is the kit appearing now? Because Mac OS X is finally popular enough so that it's a tempting economic target. A paper back in 2008 estimated that Mac OS X would be targeted when it reached 16% market share --- which is what it now has in several countries, including the U.S.

Adam O'Donnell, chief architect of the cloud technology group at SourceFire, notes that "What is happening is that people are testing the waters. It just becomes economically viable to do it, so you start seeing these attacks becoming more common."