I have just released a set of addons for the CMS Plone, done in collaboration with CIRB:
collective.linguaanalytics
This addon override the well known collective.googleanalytics to let you have a different tracking code depending on the language. You also can use it on mono language website if you want to remove oauth stuff from it and just have to drop a tracking code.
collective.linguadomains
This addon let you have one domain per language and force the user to stay on the corresponding domains depends on the waited language. This addon is really needed when you don't use navigationroot feature of the CMS (folder /fr, /en, ...). This will prevent you to have all content for each translated domains appears in google results. It is well to also used following addon if you are in that use case.
collective.linguasitemap
This addon add one sitemap per language. By definition a sitemap do not depend on the language and must provide all the content. But this is not the case if you have translated domains.