My wife and I are getting divorced but she's 7 1/2 months pregnant with my child. She's saying she doesn't want me at the hospital and won't let me see my son. What are my legal right here and what course should I take?

First, please pay more attention to posting guidelines. There is a Read First sticky at the top of the Children forum (where this was moved from) which directs questions of a legal nature here.

She can keep you from the hospital, but not from your child. Talk to your divorce attorney. As soon as the child is born you apply for joint custody with visitation rights.

Yes, you could have though your attorney paper work ready to file asking for joint custody and perhaps an emergancy order for visits.
Normally in many states you can not even finalise the divorce till the child is born due to child support and visit issues