Any chance you've been doing any other work near that left kick panel in the drivers' foot well? There are a couple of wiring connectors, a seperate ground connector, and a noise supression filter in that area that, if unplugged, could be interrupting your taillight circuit.
Other than that area, a few connectors that could cause problems if not connected properly are located in the left and right rear cargo area behind the trim panels, and at the center of the rear roof panel behind the trim panel. (There's also a second noise supression filter and an additional ground connection behind the center of the rear roof panel trim panel that both play a part in the brake light circuit).
Then again, are all of the bulbs in your taillights good? Sometimes if you're lucky it's just something simple like that.
**Not sure about that plug in the picture. Is it one of the connectors that comes out of the transmission?**