This comment on Slashdot sums it up nicely:
To get infected, you have to:1) Go to a porn site
2) Download a plugin from the porn site
3) Click “OK” that you are downloading a .DMG file.
4) Mount the .DMG
5) Go back to the Finder
6) Double-click the installer
7) Type in your account password
8) Click next a few times
So if you’re a porn-lovin’, Mac-usin’, Safari-browsin’ total fucking moron, beware!