A reasonable compromise is Mac laptop for office tasks, and a VM for development, and then a desktop development machine. If someone is super mobile as a developer, I could see a Linux laptop as an option.

The annoying thing is that if you really want security, you are basically stuck with Windows 7 or Windows 8 now, at least for desktop/laptops, and iOS or BB for phones. (Windows and platform management has gotten better -- OS X is actually the least secure OS in a major corporate environment today, due to lack of security and management tools. It's still decent for unmanaged use vs. Windows or Linux.)

In an environment processing highly sensitive information (say, a law firm working on M&As, or a print shop handling annual reports), where the tools aren't that essential to work, you could have a legitimate "you must use only our locked down systems" argument. I wouldn't really want to work in a place like that, though.

The long-term solution in high security environments is probably a mobile-based OS for desktop/tablet/mobile use, and then virtual desktop into either a super locked down existing desktop OS, or some new environment. For a lot of stuff, locked-down tablet/mobile (or ChromeOS) connecting to SaaS apps could probably do it.