With my first, I had a very small shower. We were in the process of moving at the time, so I didn't have a big work crowd to pull from, and neither did my husband, and we we hadn't joined a church yet either.
With my 2nd, I had formed close friendships w/ a group of mamas- we had met at parent/child classes my community offered. From our first class, we clicked as a group, and we remain good friends today. At that time most of us only had one (or 2, there were a couple sets of twins), but several of us have had #2 (and now 2 of us are on #3). When the round of 2nd babies started, this was a topic that we discussed. We didn't want "showers", but we wanted to celebrate the pregnancy, and we felt that *all* babies should be celebrated, no matter their birth order. Our celebration evolved into a mama's night out- we'd go get pedicures, where we'd bring in sparkling cider and treats, we'd go out to dinner. Most of us chipped in together to get the mama a gift card to her favorite store- so she could get what she needed either before the baby came or after. Some of us went on our own and got or made a gift for the mama/baby. When it was my turn, altough I knew it was coming (I was the 4th to have #2!), but it was still very special to me. I felt honored and blessed to have such good women in my life. One of them made (knit) me a beautiful little hat, and it was one of my favorite gifts, ever. After the baby came, the same group all brought my family meals as well (as I did for them when they had theirs).
That said, that's the only sort of "shower" i've ever been to for a 2nd child, and it was just within our little group. And I've known a TON of women who have had 2nd, 3rd, 4th babies.
I think it really depends on the situation, if it's normal in your area/social group/etc.