I applied for Global Entry from the U.S. Customs and Border Protection. It is one of the Trusted Traveler Programs that makes it easier to go through customs on entering the country. Global Entry also includes TSA PreCheck which helps get through security at airports.
I applied on April 13th and received conditional approval four days later. The next step is to schedule and then go to the interview. I had one or two interview time slots available right away but I could not make those so I scheduled it for a few weeks later.
The online application is very thorough, it asks a lot of questions and history. But it was easy to complete and I was able to fill it out using only my iPhone with Mobile Safari.
I'll update this post after I finish the interview but so far it's been pretty quick and painless.
I did my interview at Phoenix Sky Harbor International Airport. The interview office is in terminal 4 in the baggage claim area. Make sure you are at the Global Entry door. If I remember correctly one side is for TSA Precheck and the other side is for Global Entry. The process is straight forward: show up at your appointment time and wait in the seats outside the interview room, they'll call your name, talk one-on-one with an officer or TSA authority, and then find out whether or not you are approved. I was approved and they gave me my ID number. You can immediately use your privileges but have to wait to receive your ID card. I received my Global Entry card in the mail less than two weeks later.