All of the Grand Theft Auto games have been rated CERO Z so this isn’t really a shocker. However, Chinatown Wars will be the first Nintendo DS game with the rating and the second CERO Z game on a Nintendo platform. Killer 7 from Capcom is the other CERO Z rated game on Nintendo hardware.
Capcom usually publishes Grand Theft Auto games in Japan, but they are not handling Chinatown Wars. Cyberfront, the company that published the PC version of Grand Theft Auto IV and the Princess Maker series, will take care of Chinatown Wars in Japan.
Grand Theft Auto: Chinatown Wars has often been used as a centerpiece in a debate if M-rated DS games will sell. This fall Chinatown Wars will also be a litmus test for 18+ Nintendo DS games in Japan too.