Ok - right up front I'll tell you that I'm asking this question for semi-professional reasons. I'm hosting a cooking web forum and one of the posters has asked me if cookies or cakes with a butter or milk-based frosting need to be refrigerated.
Truth is, I personally would refrigerate if I had the room in my refrigerator or if the weather were very warm. But I don't think I'd obsess over it if the house were winter-temperature cool and my fridge were full.
I defer to the more safety-minded among you. Is it safe to leave frosted cakes un-refrigerated?
I will credit this answer to the great minds of Chowhound.