It varies a lot across the company. The great majority use very boring company-provided laptops running Linux natively, but a significant number use personally owned machines - usually Macs. Over on the JBoss side, it seems to be all Macs all the time. However, that doesn't mean the development is actually happening on the same machine as code editing or web browsing. Even with a Linux laptop, there's often a need to run a very specific version of RHEL for all testing. If you're running Fedora, that's not going to cut it, so the habit everywhere is to use VMs or machines in a lab somewhere for the actual work.