I'm working off-site today, running RDP on my Mac to connect to my Windows 7 desktop, on which I'm running a development environment in a virtual machine (Lubuntu), and from there connecting via SSH to one of our servers. So that's 3 physical computers plus one virtual computer just for me to process the latest batch of test files from our project to digitize ten more years of the British Colonist newspaper. Since I have a lot of the same applications running in each of these environments, I sometimes get confused as to where I am. Kind of like one of those sf novels where the characters find themselves buried several layers down in nested virtual realities, except not as interesting.
It never fails to amaze me how well this kind of thing works, although given the power of the hardware at my disposal these days I don't know why it should. Back in the day (2001) I recall running cygwin on Windows 2000 in VMware on Mac OS 9 (one of those bondi-blue iMacs); now that was a house of cards ...