As reported yesterday by Computerworld, there are two malware threats for OS X to concern yourself with (temporarily). The first, Tsunami, isn't much of a threat yet. The other, DevilRobber, may be slowing your Mac down as we speak. Here's more info on each of them.
Tsunami
Basically a ported version of some rather old Linux malware, Tsunami isn't being seen widely just yet. Still, the trojan appears to be evolving, and has even been updated for Ma