If you are a creative person and are forward-leaning - liking to work for companies that are flexible, innovative and even leading-edge, you might find that those types of companies will begin to make positive associations when they find out you are a Mac user - expecially if you are a knowledgeable one.
Here's why. From the beginning, Mac has been associated with the creative industries. The 1984 ad was a huge brand/lifestyle statement. The Think Different campaign associated Mac with the offbeat, maveric, innovator and genius.
We are now entering a time where innovation, disruptive technologies, thinking outside the box and creativity are actually valued as opposed to just getting paid lip service. You don't have to be a Mac user to have a rep for being visionary, creative or innovative. But, being a Mac user will be one more piece of evidence that you are on that side of the fence. Willing to use the software you think is best and break out of the norm.
Of course, I am horribly biased. But that doesn't mean I'm wrong.