Apple has reportedly included antimalware technologies in Snow Leopard, which will go on sale Friday. The news comes shortly after Apple released a fresh round of commercials indicating that the Mac, unlike PCs running Windows, is virus-free. Mac security software vendor Intego’s blog carried a screenshot showing the antimalware feature detecting a version of the RSPlug Trojan horse in a downloaded disk image. Dan Goodin, writing in the Register blog, said the feature checks for only two known Mac Trojans, and has other limitations.