My dog did great at the dog park yesterday. I let him off the leash on the trail to the dog park, and at first he ran ahead, but then immediately came back when I called him. Once at the park, he ran over to some other dogs and sniffed their butts, as a dog is wont to do. After a few minutes, they started chasing each other around.
The only problem he has is that he's a shepherd, and he nips at other animals to get them to go where he wants them to go. He nips at me, too, when I run -- not hard, but they're nips nonetheless, and it's a bit annoying. I'll have to find out how to stop him from doing that.