I've never felt like my hair has hindered my ability to get a job. I take great pride in proving the longhair stereotype wrong. It works out in funny ways. I've never been discrimanted against for my hair, people that are older than me always seem to trust me and like me more than people my age or younger. I think most of that has to do with my attitude though. I don't know.
But really, long hair shouldn't detract you getting a job. I can see how some employers might freak about it and not even want to call you back because of it, but think about it: would you really want to work for that person anyways, if that's how they see it? Fuck no!
Hey John... try something for me... next time you get the opportunity, hold the door open for an older stranger when you're entering a store at the same time as them and smile and nod as they walk by. I'm not shitting you man, you'll be able to see their minds blow right inside their heads, and it feels good. Try it, if only once.