I have a 13in Macbook Pro and the internal speakers were not working for me. However, I plugged in my higher quality headphones and held them up to the speaker and it worked. It might work if you plugged in external speakers.

There is a similar service that does monitor your Twitter/Facebook to check for activity. It's http://www.afteridie.org . I haven't really looked into it, though.

I worked on a similar project called seNotable (mentioned by dgunn) that uses public information to determine if the user has passed a way. Seems like there are quite a few of these services.