Tesla purchases 18650 battery cells from Panasonic (the same cells I use in my e-cigarette, in fact). What they have developed, however, is a battery management system that surpasses just about everything else on the current market, and that is what other car companies (or airplane manufacturers, etc) will be licensing from them in the future.
They have a proprietary wiring solution and a cooling system that works very well at preventing problems with one or a small batch of cells from spreading to the rest of the pack. On top of that is proprietary software that manages charging this system, and allows for things like quick charging without exploding the cells, which is no small feat for 60+ kWh.
