Here's a link to a picture of the Rainbow.
Here's more about the event from the same Blog (the Neverwear Blog. If you look at the first picture here, of people listening in a tent, I am visible sitting on the grass in front of the chairs. I'm in marroon to the left of a large teal bag. There is also a really cute picture of one of the Webgoblin's children.)
I hope to post a picture of the rainbow here as well...but am waiting to hear back from the person who took the picture to see if that's all right.