For now, at least. But the principles are more general, and since I doubt the app in question will be the last of its kind, I still think it's worth passing along the following.
John Brownlee has an interesting article up on Cult of Mac about a creepy iPhone app called "Girls Around Me." If you use Facebook and Foursquare, you should definitely give it a look. Basically, the app shows you all the women around you that it can find, based on their having checked into nearby places with Foursquare. For the women it does find, it also displays what information it can grab from their respective Facebook pages.
As a result of the article, Foursquare has announced that they have effectively disabled this particular app. But, as I say, it's still an instructive read.
Here's a helpful link from that article, too: "Facebook Privacy: 10 Settings Every User Needs to Know."
P.S. As of this moment, the app is still available from the iTunes store, if you want to confirm that Foursquare's actions had the intended disabling effect.
P.P.S. (Five minutes later) Aaaaand, now it's not. Bow down before my bloggy power! ;)