We see that here:
""If (Tesla's battery structure) works, we won't have to wait for a breakthrough in battery technology to develop a relatively cheap electric vehicle," Executive Vice President Takeshi Uchiyamada, who heads Toyota's research and development, told Reuters in an interview at the Detroit auto show on Tuesday.
"It could be as low as one-third of the cost of batteries being developed by car makers, because (laptop) batteries are produced in massive volumes." Source
That 67% cost reduction includes a sophisticated liquid cooling and battery management system, and extensive internal thermal isolation, which should be at least as expensive as the Volt's battery systems, and rather more expensive than those of the much simpler Leaf systems.
The batteries being developed for vehicles should cost less than laptop batteries very soon, because it's much less expensive to manufacture larger batteries than the equivalent in the form of hundreds of tiny laptop batteries. EV volumes will grow to the point of economies of scale very quickly: if an EV like the Leaf uses the equivalent of 3,100 laptop batteries1, it only takes 85,000 EVs2, to equal the volume of about 260,000,000 laptops...
1 the Tesla has 6,813 batteries for about 53kWh - that suggests about 3,100 for the 24kWh Leaf!
2 The planned deliveries for the Volt and Leaf in 2011