We have a yellow lab, who is approaching 3 years old. Our DD is 7 months old, so she came along after the dog. He is great with her. The only concern we ever has is that he will accidently hit her with his paw and scratch her - like if he's laying on the floor next to her, and gets up quickly, I'm afraid he's accidently going to scratch her - he's got really big feet, so his nails can hurt if they get you on bare skin.
But overall he is wonderful with her. I think labs, being such friednly dogs, are generally very good with kids. I have never had any concerns abour him biting her or anything like that. Just the other day, the three of us were laying on the floor together, and DD was pulluing on his ears and his fur, and he just lay there and let her. He will also periodically just walk up to her and lick her face. When she is in her jumpy seat (one of those ones that you hang up and they jump around in) he will play with her. He knows where she can reach him and where she can't, so he'll lay or sit just within her reach, and when she jumps on him, he'll push her with his nose, making her swing in her seat. It's really cute! He is also really good with our nieces and nephews are a little older - he and our five year old nephew run up and down the hallway together. Although he does sometimes still jump on adults, he does not jump on the kids - I think it has to do with the fact that they are already down at his eye level.