I think the system just uses the car's built in beeper. It sounds just like the car's other beeps in tone, loudness, and direction. I have no idea where the unit was installed, the only visible evidence of it's existance is the sensors on the bumper. It is offered as an available option right on the Toyota.ca web site and on the Camry brochure (Canadian version) so I assumed that while it may not be a true Toyota part, it has at least been designed to integrate well with the Camry systems and that appears to be the case. The sensors are black, but I've heard they can be painted to match body colour with minimal or no reduction in functionality (I read in the siennaclub.org forum about someone doing that). The surface of the sensor is just flat plastic, no holes or anything like that.

Two climate control systems, one inside and the other at the tailpipe.

2007 Camry Hybrid (in service June 2006)
FE: 6.67L/100km or 35.3 mpg (6.11L/100km or 38.5 mpg in summer)