Official Google Blog: A new look for Google Translate for Android

Currently, you can only use Conversation Mode when translating between English and Spanish. In conversation mode, simply press the microphone for your language and start speaking. Google Translate will translate your speech and read the translation out loud. Your conversation partner can then respond in their language, and you’ll hear the translation spoken back to you. Because this technology is still in alpha, factors like regional accents, background noise or rapid speech may make it difficult to understand what you’re saying. Even with these caveats, we’re excited about the future promise of this technology to be able to help people connect across languages.

via googleblog.blogspot.com

I'm really impressed with the voice translation so far.