From Stella at http://recipecircus.com
Baking a potato in the microwave generally dries it out. If you put the potato or potatoes in a plastic bag, the bag will keep the potato moist. Do not close the bag if using a Ziploc type. Any plastic bag will do. Caution should be used in taking potatoes out of the microwave. While the bag keeps the potato moist, it also keeps the steam, which is VERY hot.
From Linda Carnation