For the purposes of translating Plumi, it is important to understand some underlying aspects of both Plone and Plumi.
Plumi is quite a minimal new Plone Product but brings together many other Plone products available to create a site.
As a result, translating Plumi itself is a smaller task than getting an entire Plumi site translated. For instance, things like the login and password translation strings are provided by the Plone Translation projects (see links below).
Plumi translation follows the Plone translation system. All master translation files for any product have .pot as their extension. From this, we make a country specific translation by copying that master file to the relevant language-code file and is given a .po extension: plumi-example.pot becomes plumi-example-id.po for Indonesian, for example.
Note that the language codes are not necessarily the same as the country codes!
For instance, my is the Malaysian country code, but the Burmese (Myanmar-ese?) language code, while mm is the Malaysian language code and is the Burmese country code (!!lols, daft)
Further differentiations are also available, the World Wide Web Consortium (W3C)'s page on this is probably the best place to find further examples.
Getting the files
To get the files to be translated:
For the backend, retrieving and saving of files, all plumi .pot and .po files are available from the plumi subversion trunk:
Similarly, the Plone translation files can be retrieved and saved here:
Tools to use
There are a number of tools that are available for translating. All of the following are available in the Ubuntu repositories and for Linux in general. Lokalize and Poedit are both available for Windows, but are untested by the Engagemedia team.