If you are a developer or a content writer you can use Zanata to translate your software strings, your interface, your help files or your documentation translated and localized into different languages.
And if you are a translator, you can use Zanata to translate materials that Authors make available to you.
Zanata is a project from Redhat 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.
A public instance of Zanata is hosted at translate.zanata.org and is ready to accept content from open source projects for translation.
Here is a short video guide on how you can get a Zanata account.
And how to request a Project on Zanata