XtremeMac has introduced an Incharge Auto Charger for the iPad. The adapter is a single piece and features a 12V cigarettelighter connector linked to an iPad dock connector via a 4ft cable.
The InCharge Auto Charger is 2.1-Amps, and features a fuse that will protect the iPad in case of power spikes. The cable is long enough so that you can even use the iPad while it is plugged into the socket. Costs 25 dollars. [link]