"While Tesla Motors still won't say they will be putting Panasonic cells in the Model S battery packs (come on guys, 'fess up!), they have announced they are working with the Japanese mega-corp. In a new press release, the two companies divulged that they will "collaborate to develop next-generation battery cells for electric vehicles." Unlike many other companies with electric vehicles that will be powered by prismatic (flat, rectangular-shaped) cells, Tesla uses the 18650 format found in most laptops and since Panasonic also seems to have this preference, it seems natural for the two to develop a working relationship. The relationship is an open one since Tesla declares itself steadfastly supplier-agnostic and the company formerly known as Matsushita Electric Industrial Co., Ltd also has many other customers."
http://green.autoblog.com/2010/01/08/tesla-motors-and-panasonic-working-together-on-battery-tech/Big news, and just what Tesla needs to lower their price point.