While in Napa for the Prius Media Preview event, Toyota held a morning session of presentations.  Included here is the audio from Chief Engineer Otsuka's presentation. 

Some of the most interesting information from the presentation was about how more than 2,000 Toyota engineers worked on the 3rd Generation Prius project.  Chief Otsuka had 100 team leaders reporting to him, who were assigned to each critical area of the car's development, such as powertrain, chassis, hybrid system, styling and safety.