WordPress Multilingual Website for CMS WordPress is a breaking edge translation plugin.

You can use as many languages as you want. RTL scripts are supported. WordPress language packs are automatically downloaded and updated.
You can translate posts, pages, media, categories, post tags, menus… Custom post types, custom taxonomies, sticky posts, and post formats, RSS feeds and all default WordPress widgets are supported.
The original content, categories, post tags as well as some other metas can be automatically copied when adding a new post or page translation. Two posts can even be synchronized to appear the same in different languages. A customizable language switcher is provided as a widget or in the nav menu.