I’ve recently re-watched your video “Do Macs need Anti-Virus software?”, and I’ve been reading up on malware for the Mac.
Basically, malware that exists for OS X can only be installed by the user – by entering the admin account name and password, right?
An example of this: there was a trojan a couple years ago called OompaLoompa (Leap A – I believe) that looked like a JPEG on the outside, but when opened it would prompt the user for the Admin account name and password.
Now, I do recommend people to install ClamXav – not to scan for Mac Malware, but for Windows Malware (so that people don’t accidentally give their friends a nasty surprise).
Btw: You mentioned Norton A/V in the video… It’s crap on Windows, no doubt that it was and still is crap on OS X. Norton cripples any PC it’s installed on.