The excerpts below are from GTS Blog:

“Today Apple is releasing its new operating system called OS X Lion. Does the name have anything to do with new localization features (L10N)? The answer is no. Apple started assigning its operating systems names of large cats a long time ago (Cougars, Tigers, Leopards and Lions are all feline creatures). But this does not mean that the new OS from Apple does not have any new language features. Here is a summary (go to the Apple site for more information):

New system languages. For the first time, the Apple operating system is available in Arabic, Czech, Turkish, and Hungarian.

The Mac talks 23 languages. You can set up your Mac to speak in any of 23 languages using the VoiceOver text-to-speech tool. VoiceOver in OS X Lion includes built-in voices that speak 23 languages: Chinese (Hong Kong), Chinese (China), Chinese (Taiwan), Danish, Dutch, English (U.S.), English (UK), English (Australia), Finnish, French (France), French (Canada), German, Italian, Japanese, Korean, Norwegian, Polish, Portuguese (Brazil), Portuguese (Portugal), Russian, Spanish (Spain), Spanish (Mexico), and Swedish.

Lion supports displaying and typing vertical text used by the Japanese and Chinese languages.

Expanded language support. Twenty new font families for document and web display of text provide support for the most common languages in the Indian subcontinent, including Bengali, Kannada, Malayalam, Oriya, Sinhala, and Telugu. Devanagari, Gujarati, Gurmukhi, Urdu, and Tamil have been expanded. And three new font families support Lao, Khmer, and Myanmar.

Chinese input method. Lion supports filtering by tones, ordering and filtering by radical or stroke count, and improved pinyin-han conversion accuracy.

Vietnamese input method. Lion supports both new and old orthography in Vietnamese. Improved

Simplified Chinese recognition. Lion includes improved accuracy for Simplified Chinese handwriting recognition, as well as an extended Simplified Chinese recognizer with Roman symbols, punctuation, and a small set of additional characters. The handwriting input window is now movable.”

See: GTS Blog