Tigert pointed me to this research demo on Multiple Object Tracking. You are first presented with a collection of 'faces' spread randomly over an area. The demo identifies several (the more the merrier) 'spies'. Then the faces go back to normal and they all start bouncing around. After a short time period, the faces stop and you then need to identify the faces that were originally identified as spies. Go ahead and try it, I'll wait...
It's a really interesting experiment in your ability to track, both through your eyes, and perception of the objects as they move about in your periphery. Perhaps it's a good indicator of "multi-taskability".
However, for me, the most striking thing I found was while playing with the object tracking, I felt just like I often do when working on several projects at once. There are some 'primary' goals, objectives I want to or need to achieve. Bouncing around with these are a bunch of other tasks that do a lot to distract: blogging, IRC, chat, cats, food, etc. Can you track the projects for the distractions?
By the way, I got a perfect scores on all the levels, so I guess that bodes well for my projects - or perhaps I just didn't go to a high-enough level of spies. :)