The Magic Paintbrush is associated with the Paint the Night Parade. If you're lucky enough to be near a park featuring that parade, you may be able to get your hands on one of these little beauties.
Like it's cousin, the Magic Wand, it's intended to function as a controller of other Made With Magic products. In that regard, it functions like the Magic Wand. However, it's unique in that it's the only current Made With Magic product with audio capabilities.
In this article, a tear down reveals the audio subsystem and describes how it functions.