If you've never been to this event, it presents some really neat photographic opportunities. Nicely dressed dancers will dance in the middle of the fountain at Heritage Park. Take a look in the albums from previous years to get an idea. The dancing starts in the evening and usually continues after dark. Bring both a wide lens to capture the entire scene and the Capitol building in the background and a longer telephoto to isolate dancers and their expressions. It's also a good opportunity to experiment with flash after the sun goes down.
I haven't received an "official" notification of the event yet, but I have it on good word that it will be on this date and time.