Ron, it might be the first Mac worm, but anti-virus software for the Mac has been around a long time. The smaller installed base assures that the Mac OS won't be the primary target. Doesn't mean it's not a target at all though.
There was a guy at the Gila Bend rally that indicated that when he went to the Mac he was under the impression he would not have to concern himself with viruses but that has not been the case. Now I wouldn't know because I am NOT an apple fan.