The charger is built into the car, you just need a power outlet to plug into. The power cable is modular and has adaptors for different outlets.
* NEMA 5-15, a standard 120 outlet, will recharge at the rate of 3 miles per hour
* NEMA 5-20, a standard 120 outlet that supports more amps, will recharge at the rate of 4 miles per hour
* NEMA 14-50, a standard 240 outlet (used for electric stoves), will recharge at the rate of 29 miles per hour
For people with short enough commutes, a standard 120 outlet will work just fine, else just get a NEMA 14-50 installed in your garage.
Rates from Telsa's Model S Charging Guide (click on Adapter Guide in the Outlet Charging section).
Adapters for other standard outlets are available though sadly they dropped the NEMA 14-30 one, which is typically used for electric cloths dryers (which would have been handy when visiting family).