There are plugins that can do this, I believe. Look for ones for WPMU.
If you put in the language packs, the users can just go pick from the dropdown in their profile (Users -> Profile)
http://wpmututorials.com/how-to/localization/
download languages
upload in wp-content/language
now your dashboard is multi language
but you can make available your home page for all language like my website with many plugins
I only have .po file … How do i use that?
Okay i got that working… but my WP Admin is converted to new lang? How do i change that back to English ?
I cant find any option…
did you define a new language in your config file? If so, that did it. 😉
There shoudl be a drop-down on your User – Profile page.
I use qtranslate, and default it to Spanish for my WP UI languages can be changed within the UI.
http://ww.wp.xz.cn/extend/plugins/qtranslate/
Qtranslate has a great support forum also.
One advice though is to not upgrade WP until qtrans upgrades first.