The test is administered by Japan Education Exchanges and Services, inside Japan, and by the Japan Foundation outside Japan.
The test date for 2005 is Sunday December 4 and the application period is July 4 - September 5.
In the UK the test is administered by SOAS Language Centre, University of London, on behalf of the Japan Foundation.
A good resource for studying the necessary kanji content of the test is Kanji Clinic
Further details on the JLPT test