Over a year ago, XM announced their NavTraffic system, and it was included in the Acura RL. Alpine just released an aftermarket headunit that integrates XMs feed into their navigation system. The HCE-100XM connects to one of their navigation units, and provides traffic data. With this data travel can be routed around traffic congestion automatically.
I personally would not buy one of these for my self, as I don't like how the after market headunits have screens that pop out of the dash. What I would by is a replacement Navigation control unit that would replace the one that came with our Odyssey. With this I would still want to be able to use the builtin touchscreen display.