I'm still very much on the side of the fence that says this isn't going to happen next week and it seems like Roopesh Chander agrees. He brings up some great points on why implementing this would be very challenging. Status bar issues, edge swipe issues, keyboard issues and none of them have a clear solution. Edge swipes are probably easiest to fix (if the swipe starts in the other app but then moves, it gets cancelled and occurs as an edge swipe in the other) but even if that happens, this is just going to feel too weird. I'm sticking with a no prediction on this.
If there is a downside to Facebook's Pop library it's that it is missing an example project. André Schneider has taken on that problem and produced this project with several examples of getting this going inside your app.
It should be blindingly obvious, and expected, that Apple don't play by the same rules that we have to (for example, sandboxing and all of their Mac apps) but I did like Mark Sands' investigation into how iBooks & iTunes U get to use UIPopoverController on the iPhone. I agree with Kyle Richter that there is no scandal here though, public APIs live (almost) forever and it's certainly not an attempt to gain any kind of competitive advantage (they have that already 😉).