There are no viruses in the wild that can infect a Mac. The answer therefore, is no. There have been several malware Trojans which can easily be avoided. Read through this entire thread and Sticky.
Hmmmm ...... with all due respect but it is not because something has not happened in the past that it can not happen in the next 5 minutes ( so to speak )
The answer to both questions of "Taint it sweet " is definitely YES and not NO as you suggested.
When you question if the malware is successful today on OS X, that is a totally different ballgame.
It also strikes me that still today, denial and obscurity are used every time when answering questions on malware.
Then the semantics kick in by saying that a virus is not a trojan and vice versa. Whilst technically correct, an end-user doesn't care.
When the damage is done, it doesn't matter if it was a virus or a trojan does it ?
The quotes that your Mac runs on Unix so don't worry is also ...... well ....cutting corners.
People forget how many layers of code are written on top of Unix to make it OS X.
OS X is definitely more robust than other OS'es .... very true.
The biggest threat to OS X ( and yourself ) is what I call Layer 8 of the OSI model, the layer between the chair and the keyboard.
The bad guys will be most successful by simply asking you for your credentials and tricking you into disclosing them ..... hey let's face it, people talk and very often the mouse is faster than the brain.
You will have to be vigilant without being paranoid.
Keep your system and applications up to date at all times.
Update Adobe and Java stuff directly from their respective websites and not through some fancy looking pop-up window.
For applications and/or plug-ins ..... if you did not specifically went looking for it, don't install it.
Think before you type your password.
When in doubt, force-quit an installer and do not trust the logic behind the " No " or " Cancel " buttons.
Do you really need to operate your computer with " Admin " privileges ? ... convenient I know.
These are just a few of the things you can keep in mind in order to lower the threat level.
Don't get me wrong .... and by all means enjoy every minute of OS X ... I know I do.
Cheers ... McBie