iPhone: Purple Apps

All GUI applications on the iPhone are referred to as Purple apps. The reason isn't that surprising. Purple 2 was the iPhone's development codename.

Purple applications are built around the UIApplication class and handle the application event loop. Although you do not need to create an application package for purple applications, they work best when added into a properly formatted .app bundle and placed into an iPhone or iPod touch's /Applications folder.

One presumes that the February SDK will introduce a user ~/Applications folder as well as the existing global one as I doubt Apple will continue to let user applications run as root.