Some six months before the all-electric Nissan Leaf is set to hit the market, it has already sold out. That's right, according to Nissan CEO Carlos Ghosn, as reported by the Detroit Free Press, the car has received 13,000 orders for the car that is set to release by the end of 2010, the total allotment of Leafs headed to the U.S.

This fact, certainly good news for Nissan, may perhaps lend some weight to argument that there is a demand in this country for an affordable electric vehicle. But does it mean long-term success for other such vehicles? That is obviously the big question for car makers, scrambling to find their own place in this select niche, but this early success doesn't tell us much.

First of all, these 13,000 orders aren't actual purchases, merely advance orders coupled with a $99 refundable deposit. What happens when these 13,000 vehicles land on our shores may be a different story.

More importantly, however, these early orders may only represent the existing segment of the market for electric vehicles. Once these early adopters have slaked their thirst at the electric car well, will there be more demand for further cars from other manufacturers?

There are too many variables to know for sure right now, least of which will be gas prices, battery technology, the economic state of this country, and so forth.