Back in August 2008, Google launched a Google Translate HTML5 web app for iPhone. Now, the official Google Translate for iPhone app is available for download from App Store. The new app has all of the features of the web app and some significant new additions designed to improve the overall translation experience.
• Speak to translate
• Listen to your translations
• Full-screen mode
And the app also includes all of the major features of the web app, including the ability to view dictionary results of single words, accessing your starred translations and translation history even when offline and also support romanized text like Pinyin and Romaji.