Make sure every time the dog and baby are in the same room, it's a positive experience for your dog. Toss really good treats at him, so he'll be thinking "Wow, everytime this funny looking noisy creature is around, I get something good!" Make the treat something fabulous that he ONLY gets when baby is near and he is behaving.
You can also check out this link. Tons of great info on kids and dogs!
http://www.wonderpuppy.net/canwehelp/kids.htm