Yeah; I run in the rain, as long as it's not cold rain–you know–like rain in the winter time, and if it's not storming.
I run first thing in the morning, right after drinking a glass of water, a cup or two of coffee, some biological necessities, and dynamic stretching. I'm usually out the door by 5:30 am, so it's not a very popular time for a rain shower, especially in the summer, but it happened on my last run.
Sure, it's fun. I didn't get hot, and I wear pretty snug clothes, so I didn't get weighted down.