Computers are not really able to multitask either, except for true parrallel processing machines. They usually just assign small amounts of time to different task, just like you mention people that claim to be multitaskers do.

However the one things computers do that we could learn from is interrupt driven switching of tasks. ALthough I'm pretty sure I saw interrupt driven work mentioned here at some stage.

As an example, I often find myself waiting for things to finish compiling, or simulations to run, or even web pages to load when the net is overloaded at my University. So I may not really doing multiple things personally, but I'm waiting for tasks to complete on my computer and dealing with them as they come around. The computer is doing multitasking for me :)