It's a great little trick, and one worth adding to your development arsenal. Be aware that UIGlassButton is a private class, and one that has long since been relegated away from the official SDK development path. Although it continues to work on the Simulator, it's not for use on the iPhone itself or in App Store projects.
Continue reading on to find the code. Don't forget to substitute your own user folder into the code (in my case, "ericasadun") for Jonathan's ("schwa").