A trojan does not a virus make, so the threat of malware on the Mac is not growing. A trojan is malware which the user installs on a Mac, thinking the downloaded file is something useful. The latest trojan was found by McAfee Alert Labs. From Digital Trends:
Although attack numbers remain small, Mac users are advised to still take basic security measures, including not downloading files or attachments they feel to be suspicious.
Duh!