Believe it or not, Picasa Web Albums is a big success outside US and, since the interface is available in 38 languages, many people post comments in their native languages. Click on a featured photo and you'll certainly see at least a comment written in Spanish, Italian, Chinese, French or other language.
Google's photo-sharing service started to use Google Translate API to automatically translate comments in your interface's language. The translation is displayed below the original comment.
Of course, the translation is not perfect and Google didn't do a good job at properly disclosing that it's an automatic translation (there's a "Powered by Google Translate" tooltip when you hover over the translation). This is yet another integration of Google Translate in Google's services, after translating Google Reader subscriptions and YouTube's search results. What other services would you like to integrate machine translation?