Go to this translated page by Google. Now, mouse over some of the words in the middle of the page. Up comes a dialog box that offers the original, untranslated, version of the text, with an option to "suggest a better translation."
Click on the "contribute" button to send and Google says:
Thank you for contributing your translation suggestion to Google Translate.
This is not a new feature, Google announced it back in March. Google said they used your suggestions to "improve translation quality in future updates to our service." But it does seem that Google has expanded this feature to more languages outside of the official launch.
Forum discussion at WebmasterWorld.