Just walking around you can see who is using
Unix/Linux and who is not.
Granted most of it is embedded or SoC but they are definitely not Apple or
Mac OS's on the clear majority of the hardware solutions. Unfortunately
for us in the proprietary world it's not "cool" to talk about where you
get your firmware/software from so no one is promoting that information.
Lionstracs seem to be fairly open about being based upon Linux.
http://www.lionstracs.com/