The only difference between an exploit for a normal linux / bsd box and the apple box is the CPU anrchitecture, if your attacker knows PPC assembly (first grade computer engineering or perhaps less) he will be able to port the exploit for the apple's box. Of course, it's better to port it to sparc, so you can get some real box instead of a G4 toaster.
G4 rules, but it's for graphics design and video / music editing.