Sgt_Brony sent this image of the new Derpy promo over, just in case you were all curious about her official description. While she doesn't have a name specifically pointed out, her description is pretty accurate to her usual fandom definition! Have that below, since its a bit difficult to read in the image.
"Everypony in Ponville knows this excitable mare! She might be a klutz, and maybe even a little ditzy, but she really only wants to help. She can be seen around town making deliveries and working with the weather team, but she also has a knack for showing up whenever something interesting is going on. Just don't be surprised if she eats all the muffins in your fridge if she comes over to visit!"