Yeah, not downplaying the significance of it. Just not personally worried by it enough to run around and panic (I was immune since the malware checked for XCode, and wouldn't install if it saw it). The estimate is that 600,000 represents roughly 1% of the estimated active user base, which percentage wise is larger then the 0.7% Conficker hit on the Windows side.

It's been a constant issue on Windows for, well, decades. Much more reason for proper panic there