I think while people originally saw showers as a "first baby only" tradition, times are changing and more showers are being seen as a celebration of the arrival of a new life. My very dear SIL threw me a shower for all four babies!
First baby I had the traditional shower (like a bridal shower, where all family were invited, my moms friends, my mil's friends, neighboors, etc) And I was lucky to be given so many beautiful baby things.
Second baby, SIL threw me a "Sprinkle"

. She only invited close friends and immediate family and it was a lot of fun, and I have a ton of pictures and it was a nice way to celebrate. Mostly I received clothes (I knew I was having a boy) or picture frames, or small momentos.
I was also told that I wouldn't be able to have any more children so I gave it all away. When we found out I was pregnant with baby #3 we were thrilled and because it was a girl after two boys, my SIL threw me a "Think Pink" party!

Same group of close friends and family and mostly pink clothes or blankies.
Then came baby #4 (also a mini-miracle!) and she hosted a small brunch and let people know that they didn't have to bring a gift, but to please come and help us celebrate the end of long and hard pregnancy and to share the joy. She did organize a "food shower" where all my close friends and family signed up to bring dinner one night each for the few weeks after the baby was born. That was priceless!
So I think if the expectation of the host is that you should just come and share the joy and happiness and celebrate the arrival of a baby with the expectant mother, I don't think there is ever anything wrong with second showers!
