One problem related to brake light switch has been reported for the 2010 Toyota Prius. The most recently reported issues are listed below.
The brake lights on my 2010 Toyota Prius do not illuminate under light braking. There is a very discernible "gap" after depressing the brake pedal before the brake lights illuminate. Under light braking, the brake lights will not warn the driver of the car behind me that I am actually braking. This results in people tailgating me, and sometimes sounding their horn signal at me, while I am slowing down. Once the pedal is depressed far enough -- under moderate to severe braking -- the brake lights will eventually illuminate. This has been confirmed by several CO-workers and friends who also own this model of Prius. All of our cars have the same issue with the brake light switch.