Google Calendar now supports US English, UK English, French, Italian, German, Spanish, Danish, Dutch, Norwegian, Finnish, Swedish, Russian, Chinese (Simplified), Chinese (Traditional), Korean, Japanese, Thai, Portuguese (Brazil), Portuguese (Portugal), Turkish, Hungarian, Lithuanian, Slovenian and Polish.

Editions impacted:
Standard, Premier, Education and Partner Editions

Languages impacted:
Thai, Hungarian, Lithuanian, Slovenian, and Portuguese (Portugal)

How to access what's new:
Sign in to Google Calendar, click 'Settings', and select the interface language you prefer.

For more information:
http://www.google.com/a/help/intl/en/users/calendar.html