It seems like you only see light painting in wedding photo ops and unintentionally (and then intentionally) in 4th of July sparkler shots. It's a photo hack that's well known and slightly overused. Not to mention the outcome is generally a childlike scribble of lines somewhat resembling what you were trying to write. Bitbanger Labs has created light painting on steroids that has with their pixelstick.
By prepping photos in an image editing program like Photoshop, the Pixelstick wand reads the images and displays them one line at a time. The tool itself is an aluminum plated rod that houses 198 full color RGB LEDs. The real work comes from a handbox which connects to the wand and holds the photo information on an SD card. The light painter just needs to set the correct image up in the handbox, connect it to the wand and point it length-side forward in the direction they want the image to appear.
There are also additional controls on the handbox that can work with brightness, color and direction. The SD card gathers the photo information from the wand and can be uploaded to your computer. The result is a surreal, augmented reality-like photograph.
The images are definitely worth a double-take. Luckily, they've posted some of their finished creations online. There's even a timely album dedicated to Halloween. Try passing this one off as real to friends:
Oh, the pranks that are just waiting to be played. Currently, the team is raising the funds for their first manufacturing run on Kickstarter. Donate to their campaign here.