The Application Manager is one of the service APIs provided by Palm. See Services for the complete list.
You may use these documented methods in any application.
Open a file or URL, letting the OS pick the appropriate application or viewer.
Explicitly launch the desired application, optionally passing in parameters.
Alternatively, you may wish to use a Cross-App Launch, useful for actions such as taking a picture.
These methods are (probably) only available to applications in the com.palm domain. Thus they are forbidden for applications in the official catalog.
Appears to provide a list of all apps installed on the device.