2012-05-26: Because of issues the with source code management for MediaWiki extensions, no exports of translations can be made at the moment.
Our apologies. All your translations will of course be updated as soon as the issue is resolved. (Other news...)
Namespace translation
I think that you don't need to translate the name of the Wikipedia: namespace, because this is the namespace dedicated to the project administration. The name of the namespace is I think automatically set to be the name of the project. So on English Wikipedia, it is called 'Wikipedia:' . On English Wikiquote it is called 'Wikiquote:'. When this namespace is mentioned in the messages it is referred to as the 'project' namespace, and always inside brackets, so that the software automatically converts this to the actual project name of that project, in the main language of the project.