Whew! I just now discovered this thread and tried to skim through it... there's a lot! I'm sure I missed some things, but here goes:
First, iAntiVirus is bogus and I would never trust it. A year-old post sheds some light on this:
iAntiVirus is bogus
True to form, unless I missed something, they're hyping a "threat" but don't list details, such as a list of apps that were found to contain this threat. That's because they want you to blindly buy their software and think you're safe. The fact is, no antivirus software can provide complete protection from viruses that haven't been created yet. They don't know what to look for.
Where are all the people on this forum that for years proclaimed that Mac OS was virus/spyware free and there would NEVER be viruses/spyware due to OSX being built on Linux.
As others have corrected you, no one that I recall seeing in the forum has claimed there would never be viruses or spyware. There WERE viruses on earlier versions, but there ARE no viruses in the wild that run on current Mac OS X (Leopard or Snow Leopard). That fact remains true for the moment.
Sheeeeez...I make 1 *%^&(*ing typo in my tenure here and the Mac Fanboys attack like pitbulls. Yeah, I know I meant Unix and typed Linux by accident. Again, sheeeez. If a simple typo is all you need to get yourself(ves) all wound up, you need a life.
Also, as already pointed out, Mac OS is built on UNIX, not Linux. "Unic" or "Umix" or "Uniz" or "Ynix" would be typos. "Linux" isn't a typo. It's a false statement.
"Spyware" is a more colloquial term than either "virus" or "trojan" anyway.
Don't you mean "malware"? I only say that since viruses, trojans, spyware, adware, worms, etc. are all forms of malware.
(A worm is a virus, right?)
Mac Virus/Malware Info
What a weird coincidence that this "firm" releases info about this supposedly spyware program after Google announces they are ditching windows internally.
Agreed! See
iAntiVirus is bogus
Well, it's time for all the self-proclaimed tech-savies out there to start bashing Mac OS X for no longer being virus-safe
Mac OS X is not immune to viruses. Never has been.
I'll just go ahead and install all the AV-software for the Mac out there, and hope it'll prevent me from being stupid....
Sorry, they haven't come out with iAntiStupidity yet.

For now, your Mac remains vulnerable to user actions, no matter how foolish they might be.
It's a silly argument, often made by people that don't understand Mac history.
There once was Mac viruses. Even when it's market share was lower than now. Then Apple released OSX, with a much more secure UNIX core, and hasn't had a single virus since. Spyware? Yes. Trojans? Yes. But an actual, honest to goodness virus in the wild? No.
True.
there are fewer Mac viruses etc being written, yes.
None, actually, that are in the wild.
They are harder to get installed because you have to put in your password and most folks know better yes.
You're talking about a trojan, not a virus. A virus propagates itself without user interaction required.
Intego is pretty good. I use their VirusBarrier X6. Within the year I've encountered only 1 virus which was inoculated immediately, but still. They're out there.
Name the one virus that it found. You can't, because it wasn't a virus that runs on Mac OS X.
I installed OnyX on my computer and when I tried to improve the system's performance using the freeware, a window appeared on the screen saying that in order for OnyX to operate, I need to enter the password. Is it safe to do it? Do hackers do something like that to gather password from users and/or install spyware?
OnyX is fine. It needs your password to be able to access system files. But yes, in general, be careful about where you get software, what you install and when you enter your admin password.
Just being pedantic - but your Mac can be infected with spyware without running an installer or entering your admin password.
Name one example that applies to Mac OS X.