Leveraging its Google Translate service, Gmail Labs has added yet another feature: automatic translation of incoming email. You can turn the feature on by going to Settings, Labs, Message Translation. Remember, this is a Labs feature, so consider it "beta."
Unfortunately, the only messages we have readily on hand that are not in English are spam. So we went rooting around in our Spam folder for them to show the above image. Click the link that says "Translate message to: English" and voila. Of course, you can readily change the "translate to" language. Clicking on the translation link showed us the somewhat NSFW message which, typical of spam, centered around "performance."
Still, as we said, most of us probably get the majority of our non-native language emails in the Spam folder. Still, this feature might prove useful to some, though you are at the mercy of Google Translate's not always perfect translations. It's not Star Trek's Universal Translator, after all.