The update makes mobile Gmail more robust and closer in functionality to the desktop version. Some of the updates are support for smart links (meaning that titles will appear as links for YouTube, Google Maps and Google Docs), adding and removing labels and some improvements in the mobile webapp's looks. All of these updates have been available for a while for the U.S. English version of the webapp.
The long list of newly supported languages includes: Arabic, Bulgarian, Catalan, Chinese (Traditional and Simplified), Croatian, Czech, Danish, Dutch, English (UK and American), Estonian, Filipino, Finnish, French, German, Greek, Hebrew, Hindi, Hungarian, Icelandic, Indonesian, Italian, Japanese, Korean, Latvian, Lithuanian, Malay, Norwegian (Bokmal), Polish, Portuguese (for both Portugal and Brazil), Romanian, Russian, Serbian, Slovak, Slovenian, Spanish (for both Spain and South America), Swedish, Thai, Turkish, Ukranian, Urdu and Vietnamese.
The only requirement is an iOS version of 2.2.1 or higher, while all Android versions should be supported.
source: Google Mobile Blog