The piece that I'm in awe today is the operating system provisioning system that is in the heart of the way test automation is done here. And I just learned we have open sourced (yet apparently publicized very little) the tooling for this: https://github.com/F-Secure/dvmps
Just a high level view: imagine spawning 10 000 virtual machine for test automation use on a daily basis, with each running some set of tests. It takes just seconds to have a new machine up and running, and I often find myself tempted to use on of the machines for test automation, as the manual testing reserved images wait times are calculated in minutes.
With the thought of perspectives, I go for doing a little more research on how others do this. If you're working on scales like this, would love to benchmark experiences.