It's for this reason that I use Vagrant (http://vagrantup.com/) - don't have to care what my development workstation is; I just spin up a virtual machine to hack and test in. :)
I think he means he uses a local virtualbox virtual machine for all his development stuff so he doesnt need to care about which OS (win, linux, osx) is running on his physical machine.
Totally true, though its never quite the same. VMWare, Parallels & VirtualBox are getting there but still don't quite have the performance needed for doing video or intense graphics work.
The need to virtualize graphics drivers, that then go trough standard API on the host adds an extra layer of indirection to already slow pipeline, is probably going to prevent any major gains in that area.
No, you do you CS work in OS X and your other development/web stack etc stuff in a VM.
Best of both worlds. Actually, I'd use a VM for development even if I was running Linux as my primary OS and didn't have a need for the CS suite myself.