In recent weeks, my work has reminded how fragile the ecosystem of our computers can be. Spyware, adware, viruses, worms, and trojans (all called malware) can all throw a computer into turmoil. It used to be just a Windows thing, and still pretty much is. Apple computers and machines running Linux would see the occasional malware, but most of them were just to prove that Linux and Mac users shouldn't get too comfortable, and were never released into the wild. Those that were enjoy little success as the *nix systems (Mac included) are inherently more secure as some actions necessary for the success of a virus require interaction from the user ie username and password as if to ask,"are you sure you want to do that?"
I'm afraid that Apple's move to Intel processors made the job of writing viruses for OS X a little bit easier. Intel makes a good processor, their (and AMD's) wild success is the main reason they can be exploited for reasons not dissimilar to the million monkeys at a million typewriters theory. Before you get too upset, let me explain myself: there are just tons of x86 compatible computers out there, and tons of people have the ability to develop software for x86-based machines. Hacking, smashing the stack, overflowing buffers, and all the other nasty tricks are just a small step beyond the scope of typical programming projects, and with the temptation of the Dark Side available to literally millions more developers, more viruses will be written for Intel and compatible architectures.
So, with this in mind, we see that many programmers already know the dirty tricks that work on x86's, and Apple will now be using x86 processors. So those dirty tricks will be arriving on your Mac's doorstep soon.