The most common approach is to get antibiotics during labor in the hospital, as you mention, and from what I understand that prevents the baby from being affected. I have not been through this but my former employer had it. Her son is perfectly fine, 10 years old now with no health issues whatsoever.
From what I have read, though, Group B strep bacteria come and go, so you should be tested again right before your due date to see if it resolved itself. If you test negative at the end of your pregnancy, then you don't have to do the antibiotics. If not, then you will probably want to assume you'll be on antibiotics during labor.
I've given this some thought and if I test positive for it, I will ask to be tested again in my 3rd trimester. I just wouldn't want extra antibiotics in labor if I didn't need them. :)
I tested positive for strep b with my daughter. They gave me antibiotics during labor and we spent an extra day in the hospital as a precaution. Everything was fine.
I have a friend who recently lost her baby because of Strep B, she had a stillborn baby (1st child, she was 39). Supposedly she was a healthy carrier of this bacteria and the risk for her was low... well not so low :-( So do everything you can to protect your babies!