For those of you who are using Betawiki, please update your bookmarks. Betawiki is on http://translatewiki.net now and it's performance has improved dramatically.
Betawiki can be used to translate all core messages of MediaWiki (~1900) and the messages of about 85 extensions for MediaWiki (~1100) without requiring any technical knowledge. Developers commit the work of the translators to MediaWiki so it is available in the product.
In October 2007 we have committed changes to 71 languages from Betawiki. We expect this number to grow to over 100 before Q2-2007.