The shower and baby related gifting traditions seem a little blurry. I have one child and I am expecting my second. We did not do a shower for the first, but two friends of mine wanted to do a shower for this one, so we are. With my first, we did not find out the gender (nor are we in this case), and after the baby was born a couple people brought over little things like some girly onsies to mix in with all of the gender neutral things we had for the baby. I did not expect this, nor did I expect a shower. I frequently have taken gifts to the older children when I visit a new mom, because I think they start feeling left out that every one wants to see the baby. But I tend to keep it simple (my last friend who had a baby I took fresh cookies for the 3 older kids - the mother was really appreciative that I was including them in the event).
However, on the other end of the spectrum I have know women who planned their own baby shower, and I know many women who have had multiple showers for the same baby.
I am all for gift-giving and celebrating a new life. I think that each child deserves a bit of celebration, so I am not agianst showers for subsequent children. However, I think moderation is key. A gift for baby either at the shower or the time of birth is plenty, and for many of my close friends, I like to make a meal for the family as well at the time of birth. When I was a new mom with a deployed husband, the gift of company was the one I valued most :) I think it all comes down to doing something to support and celebrate a new life and that comes in many forms - not just "stuff."