It's really, in my opinion, as chrysaphi said, about the culture fit. When I showed up to my last job interview, I was still sporting quite short hair and my nose ring. I compensated by wearing a dressy (but not a suit!), somewhat conservative interview outfit.

Later, when I was hired, I asked one of my bosses what he thought of the nose ring. He laughed and said, "we were only concerned that you were right for the position, but the nosering was a good clue that you were laid back enough to handle our work evironment."

Every company's different, but I think in the end, it's mostly about how you present yourself.

ps - if it were me, I'd probably dye my hair a more normal color, to make sure the focus was on ME during the interview, and not secretly on my hair.