"[...] GoogleAppEngineLauncher.app, a project manager for Google App Engine client work. On the Mac, the Google App Engine SDK will be delivered with this launcher from now on.

The Launcher isn't intended to replace a full-blown IDE or editor. However, basic tasks are now trivial. To create "h*ello w*orld" [ as per BLOGOSCOPED WARNING "Ooops... please go back to remove the blocked word "h#ello w#orld" if possible."], you now just type a name and click twice. And deployment of a finished application to Google is a single click away. With the Launcher, you can focus on your app instead of the tools.

The Launcher is a true native Mac application. Installing the Google App Engine SDK, embedded in the Launcher, is a drag install. App Engine projects can be added to the Launcher with drag and drop. And your deployment password is saved in a Keychain (if you want). [...]"
http://googlemac.blogspot.com/2008/05/app-engine-launcher-for-mac-os-x.html