I've been making cupcakes for a while now and I use butter icing. They come out pretty and taste nice, but they melt so quickly. Sometimes it's impossible to pipe, because the icing goes so sloppy. When I go to parties and see other cupcakes, they stay on the table all day and the icing doesn't melt.  Are they using something different? If so, does anyone know what? 
I usually add vegetable shortening to my frosting recipe so that it doesn't melt easily. I live in India and it's hot in here for crying out loud. Another helpful tip is to add 2 tsp Meringue powder to your each icing batch, that tends to avoid the weepy icing.  Hope this helps.   (Source: Years of commercial bakery experience and my fair lot of sad weepy but delicious cupcakes) 