Just another nail in the coffin of the usefulness of AV systems. And good riddance. My work computer actually has McAfee on it, which I've disabled through the registry. Don't like how slow it makes my computer. Education, people! It's better than buying useless feel-good software.
I think it's interesting to consider computer viruses and biological pathogens in terms of "optimum harmfulness." A cold virus's best strategy, for example, is to keep you awake coughing so your immune system is weak, make you sneeze and cough and have a runny nose so you spread germs, etc. But it shouldn't kill you, especially not before you pass it on. I've heard (did I read it in Guns, Germs and Steel?) that syphi…
Then people realized there was money in botnets and password stealing. The goal of those viruses is to get onto your computer and stay there as long as possible. If you notice it, you'll remove it, so it is in their best interest to avoid being noticed.
Unfortunately, a lot of them are so poorly written they are hard not to notice.