The article goes on to state that the supposed virus released in February 2006 was not a virus, they classified it as a worm.  Symantec describes it as follows:

"Indeed, in February of this year, when OSX.Leap.A was discovered the news headlines declared that it was the “First ever first ever virus for Mac OS X!” Long before the digital ink dried on those simplistic and sensational headlines our Security Response team had determined that OSX.Leap.A was a worm, and not a file-infecting virus."

In a related post, it was outlined that Sophos Security recommends that consumers should consider purchasing a Mac.  For those of you who would like to have a safe and secure operating system, rest assured that that major security software vendors have demonstrated and stated that OS X is secure from viruses.