I've heard people say it privately, and in random comments here and there, that Facebook was already doing what Path was caught doing. Because it hadn't been said publicly, I didn't have anything I felt I could respond to. But now there's an article at PC World that at least leans toward saying that what Path is doing with address books on the iPhone is nothing more than what Facebook did with their iPhone app.
I checked with Joe Hewitt, the guy who wrote the iPhone app for Facebook and asked if they did what Path is doing. He said no. It was unequivocal.
Since Joe left Facebook a few months ago, he asked me to make it clear that he can't vouch for what they're doing now.
BTW, when I quote a programmer like this, it's because I know him, and trust him. Joe and I may disagree on some things, but I would never question his ability as a developer or his honor. This came up the other day on Twitter when I quoted Brent Simmons on something he told me about iOS. I feel the same way about Brent as I do about Joe. Both are first class pros, and their word is beyond questioning.
Brent says that as an iOS developer he wouldn't read a user's address book without asking first, and he doesn't know any iOS developers who would either. So if we condone what Path has done, we're giving them an advantage that other developers are not willing to take. In other words, we've bet on the wrong horse.