T.L.
One thing to remember is that GBS is TRANSIENT. In other words, you can test positive at one visit and not at another. That being said, the standard protocol is IV antibiotics in labor, as others have posted. Infection of the baby is still very rare, but when it does occur, it can be very serious - that is why it is treated aggressively. If you do get antibiotics, make sure you eat plenty of yogurt with live acidophilus cultures, or just take acidophilus, in order to prevent yeast infections that commonly follow antibiotic treatment. Yeast can also manifest as thrush, where it gets in babies mouth via breastfeeding and can make breastfeeding painful. (Remember, breastfeeding is NOT supposed to hurt - if it does, seek help from a lactation consultant, La Leche League leader, or breastfeeding peer counselor ASAP to resolve it.)
Back to GBS, in Europe they use a less invasive protocol than antibiotics, which has been demonstrated to be as effective at preventing GBS infection of baby as our antibiotics - and it's actually something you can do yourself. Simply use a vaginal wash with Hibiclens (available at some Wal-Marts and some drugstores). Do this as you go into labor, and then about every 6 hours until the baby is born.
Incidentally, GBS affecting babies is less common in water births (and labor is usually easier and shorter).
There is really a lot of information out there if you google it.
Hope this helps.
T. - mom of 4, including 3 amazing teens, (and student/apprentice midwife)