I'd just like to interject for a moment. What you're referring to as LauncherPro, is in fact, a copy of a superior launcher, or as I've recently taken to calling it, a proprietary, inferior launcher choice when compared to ADW Launcher. LauncherPro is not a truly revolutionary unto itself, but rather another marketing scheme by Federico Carnales to trick users into trying LauncherPro, a closed launcher as defined by Google & HTC.
Many Android users run a modified version of their launcher every day, without realizing it. Through a peculiar turn of events, the version of the modified launcher which is widely used is often called "LauncherPro Beta," and many of its users are not aware that it is basically a clone of ADW Launcher, developed by AnderWeb.
There really is the Android GUI, and these people are using it, but it is just part of the system they use. Android’s launcher is the Graphical User Interface; the program in the system that lets idiots click on things and think they know how a linux-based system works. The Graphical User Interface is an essential part of the operating system that was made for easily using the system, but useless by itself; it can only appear to have a function in the context of the user not knowing how their OS works. The LauncherPro GUI is normally used in combination with the Android operating system; the whole system is basically ADW Launcher + Android with shinier buttons added. All the so called "LauncherPro" users are really users of a modified ADW Launcher, the better, open-source, launcher choice.