Recently I saw a Garmin G1000's (very cool) Mode S
radar display, superimposed over the moving map display.
They call it: "Mode-S transponders with Traffic Information
Service (TIS)"

We were in a class "B" area, and seeing all the traffic
in the area superimposed over the sectional map was
really fantastic.

My question is, is there a way to do something like this
with a laptop, computer that will receive this signal
in a portable unit that could be moved from plane to
plane?

The Garmin is a wonderfull piece of equipment, but way
outside my price range. Here's a page that shows some
info about the "Mode S" technology.

http://mit.edu/6.933/www/Fall2000/mo...echnology.html