If you had you dream job interview would you have the beard? The answer to this should be what you should do for your interview...
Just remember though, it is a small risk depending on how you do it...
I would say if you've had a beard for the past 5 years, then yes, wear it. If you're growing it out for the month, or you work in a casual job, then shave it. If it is a trendy/short beard, or scruff... shave it. It has to be a true beard.
Also, it depends on what type of haircut/how you wear your hair. Try to stay your absolute best to not look casual. You want to be ultra professional.
It also slightly depends on where you plan on working... I work in banking, and there is only one person out of over 100 with a beard. He is the type of guy that has probably had his beard for 10 years, and it ultragroomed. I get a hard time from some of the guys I work with if I don't shave for a few days. If you want to work in a business professional environment, the beard may not be a good fit unless it truly "fits" you and who you are.
It also depends on your age. It can be very challenging for a younger person to pull a beard off while remaining professional. If you are 24 then a beard may come off like you're trying to not act your age or look older. If you are 30, then it may be able to fit you more. We had an interview one time with a guy that came in with a full beard, and I have to admit I felt like it came off a bit cocky. I know that is really weird to say, but some others agreed, and he kind of looked like brett favre... so be careful.
No goatee ever, no mustache ever