For those that already have a child(ren) what are you or will be doing to prepare them for a new baby?
Even though my ds doesn't understand too much when I try to tell I'm already pointing out that his baby brother or sister is inside mommy, and that he can't bounce on my belly anymore because soon it will be too big. When we see other little babies we tell him there will be one in the house soon and he has to be quiet and gentle. Stuff like that.
Re: Preparing LO for a new baby
I've been thinking about getting DS a babydoll. They play with dolls at daycare but we don't have one at home. I'll probably show him how to hold, feed, touch gently, etc.
He usually points out babies in books and he is around little ones at day care too. Once I start to show I will probably point or pat my belly and say baby.
I'm not a mom, but honestly, I think it is a little early. Developmentally a child his age won't be able to understand something that abstract. Once your stomach is big and he can feel the baby moving he'll begin to understand.
I'd just involve him in getting things ready for the baby, which again, it is just too early imo. So when you start to do things with the nursery he can help.
The more concrete the better.
We'll miss you sweet Debbie Girl (4.21.12) and sweet Cindy Girl (8.9.12)

We've been doing the same with DS. He's absolutely enamored with babies and loves to be near my friend's LO's. We've been working on a baby in mama's belly and it's the sweetest thing when he comes up to me to put his hand on my stomach and say baby!
Additionally we've been working on brother and big brother, in conjunction with baby. I'll say soon we'll have a baby in the house and you'll be a brother. I'll ask him if he wants a baby and he says "Yeah."
I think the baby doll is a great option as well! I have a friend who's been going that route and her DS has really responded well. Especially with learning to be gentle.
It's a little too early now. Younger kids don't really have a sense of time and waiting 7 or 8 months to meet the baby is a lifetime to them. Even with DD who is 8 we are waiting to tell her until I'm further along.
As for preparing the little one-books about being a big brother, most hospitals offer sibling classes as well. As you start to buy clothes and put nursery together let him help pick some things out too and help put them away or decorate, let him pick out a special present for the LO. As the due date gets closer definitely get the doll and show him how you will be dressing the baby and changing the diaper and feeding and carrying the baby. Even when you're doing that show him how mommy will have the baby and can't always get everything for him right away because you might be feeding or something-just to prepare him.
Nothing yet.
Well, I did ask him if he wanted a baby when we were watching Toy Story 3 a few nights ago (he loves the baby in it) and he looked at me and said "Nope!". I cracked up
Definitely. I was worried about that with our dogs because they are LOUD! Apparently B got used to it when he was in my belly because he slept right through their big barking fits!