I mentioned this in another comment, but my understanding (without having worked there) is that they do not use OS X or their own hardware internally. I think

I mentioned this in another comment, but my understanding (without having worked there) is that they do not use OS X or their own hardware internally. I think that things can be quite different between orgs though, with some adopting a more enterprise-y appliance setup (NetApp Filers, InfoBlox, etc.) and others building services more like an Internet company (Linux servers and open source based services).