I can't speak for foreign airports or airlines, but there are absolutely no legal restrictions on photography at the airport, of aircraft or while in flight - absolutely none.
Some airlines, UA in particular, prohibit photography of the cabin crew or the nonsense they call "security procedures"
, but you are free to take photos of the cabin, seating or anything your heart desires out the window on UA or any other US airline or foreign airline traveling in international airspace.
There is only one category of "airport worker" with the authority to give you a hard time at the airport if you're taking pictures - the airport cop. While the law is clear - you have the unhindered right to take photos at will of the airport, ramp, aircraft, security checkpoint, security procedures, etc etc (US airports), there are quite a few cops who will try and take your camera away or threaten you with arrest if you don't stop taking photos at their command - you can either challenge them and eventually line your pockets with cash at their expense, or just back down and wait until you're away from them or onboard.
No other airport worker, be it TSA, airline or vendor has the right to interfere with your photo taking and you're free to flip them off and ignore them - all they can do is throw a hissy fit and run and call the police. If they physically try and interfere, you have the right to fight back to protect yourself and your property.
If they do it onboard, you can still ignore them as crew member instructions must be legitimate to carry the weight of federal regs, and telling you stop taking photos out the window is not a legitimate crew member instruction and can be ignored.
Obviously you must follow the prevailing rules in the country you're visiting, but as far as the USA is concerned, photo taking is not restricted in any way. Your personality will be a factor in determining how far you'd be willing to push things if confronted. Personally, I told a Delta ramp worker to go F himself and step outside if he had a problem when he "ordered" me to stand back from the security checkpoint ropes when I was seeing someone off - I wouldn't hesitate a moment to flip him the finger if he "ordered" me to stop taking photos - simply put, airport workers don't give orders - but if you're the non-confrontational type, then just practice discretion to your taste.
I take pictures with my iPhone all the time - the cabin, seats, meals, window views, etc...when I travel with my SLR, I would do the same. If I end up getting the NEX7, it will likely be on all my trips and hopefully produce some great out-the-window shots.