Mine is the non-Outlands BC areas in northern EK.
- You can't get there through the instance portal in northern EPL, because there's an invisible wall (prevents flying too).
- If you take a fp to Zul'Aman, you will make it past the invisible wall, get to the loading screen, and wake up dead in Westfall (with your corpse at Light's Hope).
- If you take the fp to Quel'Danas, you'll get a loading screen at the gates of IF, and land safely on the isle shortly thereafter (yay!).
- Buuut...if you then fly FROM Zul'Aman south...you get through the instance portal, load safely in EPL, and shortly thereafter are killed off the taxi and end up back in Westfall dead again.
I've never been killed off a taxi before.
For the curious, neither the blood elf nor the draenei areas seem to have been updated yet. There's no flying allowed in BC areas where you weren't allowed already.