From The Apple Wiki

MIDINetSetup is an application that is typically shipped with devices running SwitchBoard, and various internal builds. The actual app though is never shown on devices running SwitchBoard, as it is found in the /Applications directory of internal builds. It is believed that it is used to set up some form of MIDI syncing, but there is no definitive way to test this as the app is seemingly non-functional on stock builds of iOS. You are allowed to "accept" some form of connections either from nobody, contacts only or from everybody, similar to Apple's AirDrop feature. The app has no icon.

The contents of the .app:

   Info.plist			_CodeSignature
   MIDIDirEntryView.nib		_internal_DirEntry.png
   MIDINetSetup			_internal_greenplus.png
   MIDINetSetupView.nib		_internal_notes.png
   MainWindow.nib		_internal_status-available.png