Any excuse to make an LED matrix is good. Instructibles user BrokenPipe says he was making a one-man version of the Disney Electrical Parade, but we all know that is just whatever happened to sound good enough at the time. It's OK, BrokenPipe. You can just tell us you wanted to make a wearable LED matrix. We think it's pretty cool!
As he explains in his step-by-step instructible, he used an LED matrix board designed by Modern Device. I couldn't find the exact LED driver board he used, but you're free to try to find it on their site. The 8x8 driver board was nowhere near large enough for what he wanted to do, so he ended up using a plastic tray with holes drilled in it.
Ping pong balls act as diffusers, giving a very nice effect. You can see in the video below that the result is quite nice.
He wired the LEDs to his 8x8 driver board with a huge mess of wire, and used an Arduino to run the entire thing. He could have added a battery and stopped here, having a nice, fun display to show off. However, it wouldn't really be a parade without music, would it?
He ended up including a laptop in the assembly that drives some external speakers as well as relaying commands to the Arduino to allow synchronized display. The IR remote you see in the video is a nice addition as well.