Actually, if you want to get technical about it,
L1 = 120v AC to onboard charger
L2 = 208v to 240v AC to onboard charger
L3 = [not currently defined]
The L3 term was used at one time by the American standards committee for a proposed variable high voltage DC with an offboard charger, but they have stopped using the term for that, though they are still trying to produce a standard. Meanwhile, a Japanese consortium, including Nissan, did produce a standard for high voltage DC with an offboard charger which has been adopted there. It is formally called CHAdeMO, and is referred to by Nissan and others as "Quick Charge". Pressure is being put on the American committee to adopt that standard, but they are resisting, still wanting to push their own with a single port that can accept all three types of current.
So QC never was, and is not now, L3. It may, or may not ever, become standard in the US. At the moment there is one CHAdeMO charger installed in California and it is not operational. (There are a few elsewhere in the US, and promises to install more in California.)
End of April 2013: Traded my 2011 SL for a 2013 S with charge pkg.