Only for entry into the US. I sure WISH it would apply to other countries--that would be truly GLOBAL. I guess it's a question of what your time is worth. I think it's good value to pay $20 a year for 2+ entries, based on some immigration lines I've seen (ATL and JFK, in particular)
When I read that some travelers are in line for 1-2 hours--that's value in my book.
Considering I "reenter" the US 10+ times a year, it's a bargain!!
I just read the info on Global Entry and the process looks a little difficult if you are not close by a major airport.