Symantec has reportedly received proof-of-concept code for a new Mac OS X virus, which they've dubbed OSX.Macarena. According to Symantec, the OSX.Macarena virus "infects other files when they are executed in the current directory, regardless of file name or extension." The fact that it will infect any type of file is pretty interesting. In the PC-world, viruses tend to target specific types of files.
The OSX.Macarena virus is the 6th Mac virus reported since February '06. The first was the Leap.A virus/worm that infected local files and spread via iChat. Leap.A was followed quickly by the Inqtana worm which spreads via Bluetooth. The fourth variant of Inqtana was reported just days ago, on October 25th, but - like OSX.Macarena - is proof-of-concept code and thus poses little to no threat.