eBay Now is eBay's local, same day delivery service. In this use case, Senior Architect Ted Dziuba discussed his use of Docker in a continuous integration process. Today, he uses Docker to implement an efficient, automated path from the developer's laptop through test and QA.
Mailgun is an email service (recently purchased by Rackspace) that allows you to send, receive and track emails effortlessly. Mailgun has made significant investments in building a Docker-centric continuous integration system for this service where high-availbility is a requirement.