One of the many new features of the upcoming Drupal 4.5.0 release is an improved localization system (locale.module). It provides an easy-to-use interface to upload translated strings into Drupal's user interface using the popular GNU gettext PO format. This will enable users to share their translations and distribute the effort of translating Drupal.

Information on what PO files are and how to use them is provided in the newly created Translator's guide section of the Drupal handbook.

You may read about translating Drupal or join the discussion in the new translations section of our forums.

Quite a few translation projects have already been created. Most of the translations aren't complete yet, so step forward and contribute!

You can download existing work-in-progress translations from the download page and file issues against them if you should find better translations or have translated more strings.