At the Tesla Motors shareholders meeting a couple days ago, Elon Musk talked at length about the business projections for the company, as well as the charging system on the Model S, and even potential for integrating solar power with the super charger system. You can view the video below, and two articles I wrote up on the meeting.
The Model S, because it has such a large battery pack, needs high power charging. Higher power than is typical among electric cars currently. The built-in charger supports a 10 kilowatt charge rate, or by option a 20 kilowatt charge rate. Additionally there is a "Super Charger" that Tesla has designed that's incompatible with the two competing quick charging systems (CHADEMO and SAE Combo Plug). It means that Tesla Model S/X owners will have cars incompatible with the quick charging networks being installed currently.