Here’s a technology idea: combine a solid-state flash drive, a synchronization engine, advanced virtual memory techniques, and a portable hardware abstraction layer to create a portable computer state device.
The idea would be like this: you have a small hardware device that you bring with your anywhere. When you plug it into one of your computers, it would synchronize the filesystem states, restore memory images, and resume your computing environment the way you left it at the last location.
It’s roughly equivalent to the idea of network computers, except you don’t need the ubiquitous ultra-high-speed Internet that doesn’t really exist (when wireless gigabit is pervasive, this would become passe).
Current reasons this can’t work, using linux as the obvious OS to start with, include the lack of an abstract HAL (root drive, home drive, etc) and the lack of virtual-memory restore on a per-process basis. Lots of the other parts exist already.
Initial limitations would probably be a restriction to the same hardware architecture (x86, AMD64, ARM, etc), inability to deal with filesystem changes greater than the capacity of the SSD, and an inability to restore stateful network connections (an IP proxy might work around the last one).
One company has made an approach at this experience by running the environment directly on the portable device, but this forfeits local resources and demands power draws unachievable on an external bus (for simple connectivity). That approach may gain viability over time, though, but not yet.
Would you, gentle reader, use such a device?