I haven't seen it in use anywhere I've worked.....
.... or maybe it's just difficult to spot...
OpenStack Dalmatian, the 30th edition of the open source cloud stack, has bounded out of the kennel. The Open InfraFoundation, which tends the project, is excited about this release amid what it calls "a significant surge in adoption, attributed largely to the software's popularity as a VMware alternative." The stack also …
It isn't as prevalent as some other tools out there, but it *does* get a fair bit of use. It is frequently well hidden as far as end users and even some middle level IT admins perspective. It is awesome once deployed and tuned. Makes some of the virtualization platforms look positively archaic.