This is going to be my Global Entry backup. Here's how it works. Once you land, connect to wireless or wi-fi and submit your data to Customs. Within a few seconds, you will receive a receipt with an encrypted barcode which is valid for 4 hours. Follow the mobile passport control signs and skip the lines! Show your passport to the CBP officer and scan the barcode and you'll be on your way! Right now it's only available in Seattle, San Francisco, Chicago, Atlanta, and Miami but definitely worth a try if you're coming through one of those airports.
Has anyone used this before? I'd love to hear your feedback!