I have only ever attended showers like this, but around here, they are called display showers. (in invitation it says "Display Shower. No Gift Wrap Necessary.")
What happens is this :
Guests show up with gifts. Hosts put gifts on tables on display in categories. (Feeding items together, etc.) Hosts also write down who brought what (so writing Thank Yous will be easier!)
This leaves more time for eating and socializing and games, perhaps.
If guests would like to see mom-to-be (or bride-to-be's) gifts, they can get up and check them out.
It's nice bc then you don't have to sit around and watch the mom or bride-to-be open every single gift and "ooh and ahh" over every single little item.
I was told that a lot of folks around here do display showers bc it is easier on the guests and more guests are likely to show up, plus no paper is wasted. Who knows? Everyone does showers differently, I am sure.
Good luck...I hope this helps! :)