Introduced this week was a new button on the privacy settings on a user's page, in which they share their Facebook information with anyone at all on the Web. It's shared by default.
There is also a loophole in which linking pages - like those of Facebook friends - which have the setting switched on will also share the contents of their linked pages. In other words if you set your settings to switched off, then I become your Facebook friend and mine are on, then hard luck - you're searchable because you're linked to me.
Next to nobody has had an official notification about this. I found out from a Twitter note.
It's unsurprising, given the reaction, that the whole thing is under review. Daniweb will of course keep you posted.