Do not refer to her as being a "baby" anymore... Only the "big girl" :-)
Get a couple books about big sisters and brothers and make those your nightly reading...
Who is staying with her at home? Talk it up!!! Plan stuff for them to do that you know she LOVES.
Have them go to the store and buy a little "present" for the baby. Make sure to tell the adult to let her make the final decision, help wrap it, and bring it in.
Call the hospital. A lot of times on a slow day the nurses will more than happily show you around the maternity area... I don't think she needs to see the c-section room... More of the kind of room she will visit you in. See what they say about sneaking you in for a quick visit...
Talk about how when the baby gets here your belly is going to be "ouchie" for a little while. So when she comes and visits you she can sit beside you and not feel slighted since she's not ON you... A bit of pre knowledge is awesome...
When you do have her come visit make sure YOU are NOT holding new baby and she can climb right up beside you unincumbered... Then have daddy or other adult bring baby over and introduce them.
When you go home have someone else bring baby in the house. Your arms should be open for her to hug and sit down and cuddle...
The reality of a baby of her own isn't gonna sink in fully until after baby is here... But talking about being gentle and giving her some knowledge is the best way to go...
If you havn't already, I agree with getting a babydoll and play set. Let her name her baby, and be its mommy... If your planning on nursing don't be suprized to see a baby under her shirt at some point... Don't make a big deal out of it. :-) But do insist that she treats the baby like she would THE BABY... aka, no throwing, hitting, etc.
Also, before baby comes I would go to the store and buy a few cheap toys and put them in the house... :-) Then on those days that you NEED her to settle down so you can tend the baby, there is a distraction already available...
Good luck and have fun!!!