I'm pretty excited for the upcoming release of Firefox 3 - we have been working at many improvements in the Localization approach - and this year we managed to ship over 18 locale's for Firefox 3 Beta 1 (first time we've ever done that!).
I will be working with Mike Beltzner over the next few weeks to write up guidelines for the web services like Search, RSS, etc that can be customized for local markets. These will compliment the existing Firefox 3 localization page. As an example, I recently learned that the motivation behind including the BBC feed in Firefox was to demonstrate the dynamic, fun and potentially entertaining use of embedding and RSS feed into your Firefox chrome. I had thought we chose the BBC for the comprehensiveness of the news content (which I'd previously written in some bugs). All that to say the new guidelines should enable some great local user choices that really show off Firefox well. And, I look forward to having those kinds of discussions with localizers to make Firefox more relevant in local languages.