Google Phonebook is the Google product that even they don't want you to know about. To be able to search it, you have to know the URL, you can't directly link to it, and to enter the interface you must be linked to an already completed search, such as: http://www.google.com/search?pb=r&q=Nathan+Hammond.
Even then at the bottom of every results page there is this link: Request to have your name removed from this list.
It seems to me that Google is incredibly aware of the privacy ramifications of posting public personal information in a clean and usable interface for the world to see. So why do it?
As it stands the people most likely to know about the service are the ones most likely to use it for more nefarious purposes such as information mining. Throttling requests, you could scrape every single bit of data available in that database. Or, if a thief were targeting an individual (because of some high-dollar goods they saw on Flickr) they could pair that information with Loopt, Twitter, or a public Google calendar and all of a sudden we know where somebody lives, what they own, and when they're not going to be there. Or, less maliciously, you might be able to send your grandmother a birthday card. Which do you think is more likely?
I believe that Google is doing their users a disservice by not promoting this product. It leaves individuals woefully unaware as to the availability of their information and unprepared for ways that information can be used.
This is a followup to my previous post, Privacy in the Modern Era. As a footnote, I'm still looking for a volunteer for my privacy experiment.