The second system involves the seats themselves. If an imminent rear-end collision is detected, the seat backs will automatically return to an upright position. In addition, seat belts will tighten and the headrests will move forward to help prevent whiplash. Both innovations are planned to arrive soon on Japan-market vehicles from Toyota Motor Corporation, so it's expected that these technologies will likely debut on upcoming Lexus models in the States.
[Source: Automotive News, sub. req'd]