Mac Attacks Tracks

Don't be concerned by this sensationalist story at Tech Review: Stealthier Mac Attacks. All this is is a proof-of-concept demonstration that a person can cover their tracks on a compromised system.

The technique that will be outlined at Black Hat DC allows an attacker to remove virtually all trace of an attack against OS X, after compromising the system using another exploit.

Your Mac would still have to be compromised by some other means first, before someone could then cover up what they did.