SwitchBoard OS is one of Apple’s internal utilities. It’s a simple launcher of other utilities. It is installed on the most Apple iPhone/iPad/iPod Prototypes. Generally, it’s the same set of applications (new test apps are created to test new features). There is not really a SwitchBoard binary available for public. SwitchBoard and diagnostic utilities are copied onto the device during restore from special firmware bundles which are seeded only to Apple official service centers. It may be installed onto devices through PurpleRestore. Switchboard and its internal utilities are, in fact, present on all iDevice prototypes during development. These utilities run extensive tests on the devices, including sensors, thermal measurements and more – and only when all tests pass do the devices go through a final stage, which involves removing the debug utilities and installing the stock version of iOS. It might be illegal to have such a firmware or whatever (there is no official statement, but I remember the legendary story about the lost iPhone 4 prototype) – it’s not liked by Apple’s official site.
I got an IPSW firmware with SwitchBoard Prototype OS for my iPhone 3GS and iPhone 4.
The iOS alternative can be installed untethered on regular iDevices with a Bootrom/iBoot exploit.
Here are a few images by myself: