We went out the week before and got DS to choose a present for his new sister, and there was a present waiting for him from her at the hospital.
I was really careful to meet DS in the hallway and we all walked in to meet the new baby together. I didn't want him to feel he was replaced... but that he was a part of welcoming a new addition to our family.

He is the most delightful big brother - sure they quarrel but there are no jealousy issues. I guess preperation (making him wait for things before baby arrives etc) and ensuring his routine doesn't change too much all helped I think.

HTH?