Upon reading this BBC story this morning, I came here posthaste to see what was being said about it.
I agree with cwa: I think OS X is just as safe from the types of viruses we are familiar with. What gave me pause were the last 2 paragraphs of the story:
"However, in recent months, hi-tech criminals have signalled a change in tactics away from e-mail borne viruses. Instead, many are infiltrating popular webpages in a bid to infect the machine of any and every visitor.

Many seek to steal valuable information such as login names, passwords or game accounts instead of trying to install themselves on a machine."

This brings up a couple questions: Are server-side viruses really new? It sounds like pharming attacks to me. Can installing antivirus software on your Mac defeat those kinds of attacks? Are there more important questions I'm not asking? Your analysis please!