The problem was that I made the frosting in the kitchen in the middle of the day when it was much too warm. My butter was much too soft. This frosting is meringue based, and apparently, it is very important that your butter be a specific temperature. I learned this after my frosting disaster by consulting the genius book, The Cake Bible by Rose Levy Beranbaum. According to the book, "A word of caution: If the butter is too soft or the room too hot, what could have been a satin-smooth cream breaks down into a grainy hopeless puddle". That's exactly what happened to me--a grainy, hopeless puddle. I should have scrapped the first batch of frosting and started over, but instead I tried to "repair" it by adding some powdered sugar and grated coconut. Not a huge success. The frosting tasted fine, but it kept sliding off the cake. Even as I was trying to take a photo of the completed cake, the frosting was sliding down the sides like molten lava. It was quite funny actually.
Both the cake itself, and the filling were both delicious and things I would like to make again, though next time I think I'll go with a simple cream cheese frosting--cream cheese and pineapple go well together.
The recipe for this cake comes from Sky High: Irresistible Triple-Layer Cakes by Alisa Huntsman and Peter Wynne. You can find the complete recipe here: http://docs.google.com/View?docID=dg5mng3t_76gsvmfp6x&revision=_latest
Please visit the Cake Slice blogroll to see some of the more successful versions of this cake! http://thecakeslicebakers.blogspot.com/