OzTheGreat

Adds a multiple select box to every non-admin user profile that allows admins to 
select which languages that user can see / edit in the wp-admin.
Languages that a user cannot see are hidden. If they try to switch surreptitiously 
it will throw an error message.
This plugin REQUIRES WPML and is useless without it.

WPML Editor Languages

Allows admins to restrict users to specific languages in the WordPress admin

Oleg Butuzov

For WP 2.3 – 2.5 you should user 1.3.* version
WP_Multilingual is extension that brings WordPress multilingual support. With it’s help you can publish more that in one language at a time. Its easy, cheap and simple way to use multilingual advantages of blogging.
With this plugin you can manage your Posts/Pages/Categories/Blogroll Links/Tags in multilingual mode.
Plugin also allow you to localize theme relate to Selected language, and localize Wp-admin in your language. 
Plugin Localized in
<ul>
<li>Russian</li>
<li>Ukrainian</li>
<li>English</li>
<li>Franch</li>
<li>Italian</li>
<li>Greek</li>
<li>Spanish</li>
<li>Czech</li>
<li>Catalan</li>
<li>Herbew</li>
<li>Deutsch</li>
<li>Dutch (Holland or Netherlands)</li>
<li>Arabian</li>
<li>Polish</li>
</ul>

WP_Multilingual

WP_Multilingual is extension that brings WordPress multilingual support. With it's help you can publish more that in one language at a time.

WPML Editor Languages vs WP_Multilingual