Cream Cheese Frosting
I know I should know this, but does a cake frosted with a cream cheese frosting need to be refrigerated? My common sense says yes, but if I followed that then buttercream would need to as well and I know that's not the case.
I don't think refrigeration is required from a food safety perspective. But if you are using butter in your frosting, you might want to keep the cake in a cool place so the frosting doesn't start to melt.
I found this out firsthand a few weeks ago. Living in Phoenix, I'll remember to refrigerate the cake/cupcakes next time. The frosting itself was great tasting, but it separated a bit due to the butter.
If you do decide to put it in the fridge, take it out and bring it to room temp before you serve it, as it is 100 percent better at room temp
I made my son's birthday cake with cream cheese frosting, and it did fine overnight.
That said, I made a carrot cake a few months ago with the same frosting, and after a few days at room temperature, it was definetly smelling moldy.
For food safety, you need to refrigerate cream cheese frosting. Technically, you have two hours to leave it out, but you could get away with a few more, especially if it's not sitting in a hot room. I find if I take the cake out of the fridge an hour before, it's great.