You Think That’s a Computer You’re Using?
Emulation is in a lot of places in a modern computer. At the trivial level, things like OpenGL and DirectX emulate missing functionality on graphics hardware. At the more advanced level, entire operating systems or computers are emulated for legacy support.
This situation is likely to grow, as even mainstream operating systems gain virtualization support. Eventually it’s possible that running in a completely virtualized environment will become the norm. Even today, it’s possible to keep a Xen virtual machine image on a USB flash drive and use it on any Xen-supported system where you need to work.