Uh-oh!!! I had this EXACT same problem about 6 months ago. You are looking at some serious $$$$$$$$ unless you get lucky like myself. It's the computer module in your trunk, behind the carpet on the right side wall of the trunk, next to the tail light.
Symptoms: No brake lights, won't shift out of park, tail lights won't shut off, no rear turn signals, fuel indicator shows empty, no trunk release, etc...
You CAN get it into gear though, and have someone FOLLOW you to the closest dealership. Put the key into the ON position. This will allow you to push the button on your shifter. Keep the button pressed in, while starting the car with your free hand. Once it's started, put the car into gear. Remember to have someone FOLLOW you, that knows you don't have brake lights.
In my case, they were able to reprogram the factory computer module, and it cost me $110, but that's with my hookup at Ford. If you need a new module, you're looking at over $1,000.00. Sorry to be the rain on your parade, but this is exactly what happened with my '01 LS8 Sport. Good luck, and let us know what happens!
Mark