Zanata is a web-based system for translators to translate documentation and software online using a web-browser. It is written in Java and uses modern web technologies like JBoss, Seam, GWT, Hibernate, and a REST API. It currently supports translation of DocBook/Publican documentation through PO files. Projects can be uploaded to and downloaded from a Zanata server using a Maven plugin or a Python client.
For developers and writers: By using Zanata for your document translations, you can open up your project for translations without opening your entire project in version control.
For translators: No need to deal with PO files, gettext or a version control system - just log in to the website, join a language team and start translating, with translation memory (history of similar translations) and the ability to see updates from other translators in seconds.
You can find out more about Zanata (mailing lists, bug reports, source code) at http://zanata.org/