Thanks to Naoko McCracken the WordPress Beta Tester plugin is now fully translatable and also has a Japanese translation out of the box.

Hopefully this will make it easy for Japanese WordPress users to get involved in the Beta Testing of WordPress 2.9 in the coming weeks. If you would like to submit a translation for your language then you can download the pot file from the WordPress plugins Subversion repository here: wp-beta-tester.pot. If you send me the po and mo files I will add them to the repository and release an updated version of the plugin.