It was initially being reported that there is a MAJOR security issue with Google Voice Mail. Readers at BGR are stating that a trip to
https://www.google.com/voice/fm/* in Google revealed over 30 voice mail messages belonging to various Google Voice accounts. Each revealed link showed the voice mail transcript, audio file, and even the caller's name and phone number.
However, after a little digging it seems these voice-mails were publicly posted online and have been indexed by the Google service. Here is the official word 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.”
Remember, if you don't want it known, don't put it on a computer!