It's not really a pass. Your passport basically becomes 'flagged' as Global Entry eligible because that's what you scan at the Kiosk when arriving back into the states. Give yourself about a month to get it. You first have to apply online by providing a lot of info about you. If you are accepted, they will then have you schedule an appointment to go to an airport CBP office to be interviewed and give your fingerprints.

An additional benefit to being in Global Entry is that you are also able to use the TSA Pre-Check program at airports that have it.