Google Voice Mails have been discovered in Google’s search engine, providing audio files, names, and phone 
number as if you were logged in and checking your own voice mail. Some appear to be test messages, while others are clearly not.
The Boy Genius Report explains:
After entering “site:https://www.google.com/voice/fm/*” into Google,
our reader was shocked and discouraged to be greeted by 31 voice mail
messages belonging to random Google Voice accounts. Clicking on each
revealed not only the audio file and transcript of the call, but it
also listed the callers name and phone number as it would if you were
checking your own Google Voice voice mail.
Here’s the official response from Google:
“Since the initial idea behind posting a voicemail, was precisely to
share it with others, we did not restrict crawling of those messages
that users post on the web, but we can certainly understand that users
would want to make them public on their sites but not necessarily
searchable directly outside of their own website. We made a change to
prevent those to be crawled so only the site owner can decide to index
them.”
There’s an interesting discussion on this at Slashdot.
UPDATE: Here’s a new blog post from the Google Voice team explaining the situation.
