The best place to get the answer to this question is from the actual organizers of the program at:
The JET Programme : the official word on the Japan Exchange in Teaching programme we are working on, offered by the Japanese government. Complete with pictures, a detailed description of the job types offered and application procedures.
For a more personal look at what the participants tink, take a look at
Lenore's Reflections on the JET Program
The Wanna Be JET Page
Lenore De Asis (firstname.lastname@example.org)