Not the same
"Windows malware strains dwarf Mac virus variants by several orders of magnitude, but that's not to say that Mac malware doesn't exist. VXers are taking more interest in Macs as the platform has grown in popularity."
Still, not the same threat. In Mac OS X, the trojans depend on a user downloading and installing the malicious program from a dodgy site. This involves not only a prompt to download the software, but prompts to install and enter the admin password.
If you are in the habit up updating system software with random packages offered by dubious web sites, then, well, you get what's coming to you. I'd say the same to a user of any platform.