Can opener
OS X Rootkit - includes Opener script | Adding Understanding
All of the comments I read at Macintouch are at best mis-informed. While the Opener script itself does not "infect" computers as a part of the OSXRK it can be used to exploit machines.
Worth reading, lists better ways to check to see if your Mac's been compromised than the rampant misunderstanding (as he mentions) going on over at Macintouch.
Folks, if you've been owned, all the handwaving "Everything is all right. Do not panic. It's still better than Windoze." noise in the world is not going to get you dis-owned. Shit happens, deal with it.