My 4 last employers have used desktop Linux to some extent:
Ericsson (Swedish telecoms), default was to have a Windows laptop with X server (Citrix?) but a few of us were lucky enough to get a Linux laptop.
Vector (German automotive), Linux dev. environment in a VM on Windows laptops.
Opera Software (Norwegian web browser), first day I was given a stack of components and told to assemble my PC and then install my Linux distribution of choice.
And a smaller company, which shall remain unnamed, also used Windows laptops with Linux dev. env. in VM.
Sure most of it was on top of Windows, but if you fullscreen it you can barely tell the difference :)