It was initially intended to basically allow you to pair up a laptop or phone and get GPS coordinates from the OnStar module. You could then run a navigation program like Streets & Trips on your laptop. This functionality was eventually disabled, but wasn't removed from the radio menu for some reason.
I work for GM and I designed the interface for the Camaro USB and Bluetooth audio streaming interface. Feel free to ask me any questions you have about how the USB or Bluetooth works!
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