Tonight, we're starting to roll out the new version of Gmail in 37 languages.* As we first announced when we launched in English, this version, available for IE7 and Firefox 2, has an entirely new code base, which allows us to add new features more rapidly and share components with other Google applications (we now use the same rich text editor as Groups and Page Creator, and the contact manager can be seen in several Google apps). So if you were using English, you can now change your default language from the Settings menu to take advantage of a bunch of features that have recently launched in your preferred language, including:

One side effect of this change is that it may disrupt some third-party Gmail extensions -- unsupported scripts that directly modify Gmail's code. If you don't use them, you don't need to worry about this. But if you do, we've contacted a number of the developers behind some popular extensions and many of them have updated their scripts, so make sure you're using the latest version or check back with them if you encounter any issues.

*The newest version of Gmail is not yet available for Croatian, Icelandic, Hebrew or Arabic, but you can continue using the older version in these languages. The newest version also is not yet available for Google Apps for your domain.

Updated 4/22: We're still rolling out the new version of Gmail to all languages, and we're working to have it out to all users as soon as possible.

Updated 5/5: The new version of Gmail is now fully rolled out to all users with Firefox 2 and IE7 in these languages.