The personal operating environment has always been more of a marketing fantasy than a reality. Even now, when it's possible to stick so many pieces of your digital life in the cloud you can almost reassemble (though not in usable fashion) all the resources you have at your desk, "the cloud" is a more concrete reality than the personal operating environment.
The potential – and I'll try to avoid the superlatives and automagicality of the software-vendor imaginarium in describing this because I can actually see it happening for the first time – is that all the virtualization and connectivity built into Windows 8, added to the gradual consolidation of the core functions of Windows into code that can run devices other than just a PC, will convert what most people think of as "their computer" into a virtual environment they can take with them anywhere.
Cut Windows loose from the hardware
The most basic addition is the inclusion of the Hyper-V hypervisor in Windows 8 along with native support for the VHD virtual-desktop standard and ISO files that can load as software rather than only from a CD/DVD drive.
Initially the only thing that will accomplish is to make it easier to run Citrix XenDesktop within organizations that don't want to buy the client software.
It will also turn every Windows 8 machine into a good BYOC device because the hypervisor will make it possible for IT to create the same dual-personality for a PC that is possible with smartphones and tablets divided into one virtual machine for work and another for personal data, apps and other things users like to play with but that IT would never let into a secure environment.
Building a hypervisor into an operating system does something much more profound than just offer smarter disk partitioning: it severs the connection between the operating system and the machine on which it runs.
That means, not matter how much you cram into your laptop – your schedule and data and contacts and every other thing you can't fit in your head anymore – it's not the laptop that's important. It's the data and the method you rely on to find and use the data.
The operating system that talks to the hardware doesn't even have to be the same one users take with them in their personal operating environment.
Changing the "operating system" to talk to users, not hardware
Traditionally the first job of an operating system was to talk to the hardware: tell the hard drive what to store and where, divide the memory among the applications, tell the WiFi radio what access points it can talk to and which it can't.