As an American living in Europe, I was surprised to see all land-line and mobile numbers published in our local directory (I'm in Britain) which even included a reverse look-up index so you could scan tables of numbers and see the corresponding names! That disappeared a few years back but most of the numbers are still listed if you know the person's name.
I'm all for privacy but I think the fear of having your number posted is overrated unless you have an actual reason (stalker, abusive ex, etc...) in which case a free and easy way to totally opt-out should exist. I've had my phone numbers and email address publicly posted for years and while I get the occasional weirdo, it's totally worth it for the random interesting calls from strangers.
Fist time I hear it. Where?
Basically, an online phonebook, with reverse lookup, addresses, birthdays, neighborhood data, ...