As long as you're alright with never being at the top, you'll be fine with long hair. I work in a professional environment and a few guys with long hair have pretty good jobs. There's even an engineer with long hair. However, I will say it probably depends on the type of long hair. The guys with long hair at my work are surfer/skater types. If you've got black/multicolored hair draped over your face in an oh-so-emo way, you probably won't get hired. Even if you don't work in a service setting, people generally don't enjoy working around depressing people.

Also, facial hair, in my experience, is generally irrelevant. With the exception of jobs that require you to be clean-shaven for handling/sanitary/etc reasons, facial hair is pretty much accepted from my experience.

I guess the main concern is whether or not you are around clients/customers. Businesses generally want to present themselves in the best way possible, with the exception of fast food and some low class retail stores.