I configured a bunch of iPads at my previous job, and I had to do it one at a time. Granted, there were only like 6 of them, but I am wondering what I would do if I needed to configure a whole bunch of iDevices. I know at the Apple Store they apply updates on a bunch of them without taking them out of the package, so there must be some sort of way to do this.
The Apple Configurator was made for this exact reason: easy deployment of iOS devices in large numbers.
You would do some research on the various MDM solutions that exist and then decide whether you want to hire interns and employees to do the work manually or hire some software to allow one person to automate the parts of device management you care most about.
Here's a nice place to start when you face this problem: