Mac virus? Nope.
So apparently the Mac has its first "virus-like thingy" since the advent of OS X, specifically a trojan horse that can live in an MP3 file. So far there has only been a proof-of-concept, and it hasn't been seen in the wild. Well, it turns out that this is not even a threat. You would have to download/share a binhex-encoded MP3 file, and nobody does that, so there'd be no way for this thing to spread. The anti-virus people must be banging their heads against the wall trying to think of a way to sell anti-virus software to Mac users.