As can when it happens - I think 4Square was already pretty reasonable, because they only uploaded the address book when you hit "Find my Friends using Contacts" or something like it.
Path, to me, was only particularly bad because they'd upload your contacts every time you signed in.
That's certainly true, but at some level you have to trust us right? Consider that the whole basis of foursquare is that you're telling us where you're going or using us to figure out where to go next. That information is probably a lot more sensitive than your address book.
I think we've earned that trust over the past 3 years, and will continue to earn it over and over again into the future by sticking to our word and being transparent about what happens to your data when you send it to us.
That's essentially what I'm saying. Installing an app on a phone with personally information is implicitly trusting the developers of that app. A least for technical people, it would be foolish to blindly trust a phone manufacturer's sandboxing and policies.
Facebook always stored. Even when you gave it access from the desktop to your webmail client, etc.
That's how it knows to suggest people that you should friend once you create an account for the first time and DON'T give it your address book: it stored people that had your email listed in their address books.
Path stored the data but I know 4sq does a search against it but does not store it. That can make a huge difference...