The perkamon project's goal is to help translating the Linux man-pages into other languages. And more importantly, it helps maintaining these translations up-to-date. Manual pages are converted into PO files by po4a. These are regular PO files; translators can use any tool (text editor, specialized or not, online services, etc) they like to manage their translations.
Currently the only available translations are in French. Please contact us if you want to help this translation, or are interested in starting a new language. Russian people started a man-pages-ru project on SourceForge, and German translators for Debian are actively working to update their German translation. Both teams also manage their translations with po4a, but we use slightly different frameworks.