One of the best things about the Joomla CMS and the Joomla community as a whole is that it truly tries to be global and inclusive in nature. A lot of discussion and debate surounds the issue of language availability in Joomla, and many hours of development work have gone into providing a multi-lingual experience for those using Joomla as their web platform. Over the past few months, Google's Summer of Code project has brought about even greater support for language packs in the Joomla core.
Many people worked hard to get Joomla into the GSOC program, including Javier Gomez for one. Language pack installation is now much easier than it has ever been thanks to the work done this summer. The new feature will be available in version 2.5.7 as well as all 3.0 releases.
The way it works is as follows:
A new tab is now displayed in the Extension Manager: Install Languages.
Clicking this tab prompts Joomla to check for available languages and display them in the Manager.
Click on the language or languages you want to install from the list.
You are then redirected to the "Install Languages Manager".
It's recommended not to install "too many" languages at once; however, it's not clear how many "too many" may be. Installing one or two at a time may the best route until a recommendation is made.
To read the full report on the language pack development, visit the Joomla! Community Portal.