The Myth of Multitasking
thenewatlantis.com
thenewatlantis.com
Monochronism and Polychronism have been co-opted to apply to individuals but they were coined by Hall to describe patterns of culture. A highly monochronic culture would be Germany; things happen one at a time, from start to finish, where a new thing starts. A highly polychronic culture would be a lot of latin cultures, where whatever is most important that second takes precedence, no matter when you started it (this is usually determined socially; family>customer, for example).
Most cultures are more complex than that, though. Japanese business tends to be highly polychronic in the planning stages, where a consensus must be reached and all the time in the world is taken to reach it. However, once the decision has been made, the implementation is not only wicked fast but highly monochronic.
He's worth looking into if you really want to make the leap from how multi-tasking affects individuals to how it affects complex systems.
That kind of soft context switch is fairly easy to manage. A task coming and forcing a context switch in the middle of something incurs a much higher penalty.
This is multitasking in the sense that over a period of time you will have worked on multiple things. But it isn't multitasking in the sense that you aren't doing two things at the same instant.