I'm pretty sure "load" means the power being consumed at any instant (measured in watts or kW), not the total energy (measured in kWh, which is what your bill is). I think that "3 homes" number is plausible, especially overnight - it's maybe even a underestimate. I managed to scrape together enough statistics to estimate off-peak (nighttime) usage in summer for a Long Island "household", and I got that a typical one only draws around 600 watts during the night. The Volt would use 2 "households" when charging with the stock Voltec station, and 4 "households" with a 240 V system charging over 4 hours. It might peak at 6 "households" if it's maxing out a level 2 station.
Did anyone notice the statement near the end of this article: "The load of one of the cars charging is about the equivalent of three homes in San Francisco. It’s taking that much out of the system.” Is this true? Is anyone seeing their electric bills triple?
Here's my math, in case I messed it up!
Off-peak night hours (LIPA ): 8PM-10AM weekdays, and all weekends (70% of the time)
Total off-peak hours in a summer (June, July, August, September): 122 days * 24 hours/day * 0.7 = 2050 hours
Proportion of electricity used in night time in summer : 184.7/525.5 = 25.1%
Total summer energy use for an average LI household (2006) : 4000 kWh
Estimated summer off-peak energy use (total over a summer): 4000 kWh * 0.251 = 1255 kWh
Power during summer nighttime: 1255 kWh / 2050 hours = 612 watts
A level 2 charging station draws at max 240 volts * 16 amps = 3840 watts, which would be around 6 "households".
It should average 10.4 kWh / 4 hours = 2600 watts, which is 4 "households".
The "stock" station averages 10.4 kWh / 8 hours = 1300 watts, which would be 2 "households".
 NY state stats for July 14, 2011: http://www.ferc.gov/market-oversight/mkt-electric/new-york/nyiso-rto-dly-rpt.pdf
 2006 LIPA stats: http://www.osc.state.ny.us/reports/pubauth/lipasummer06.pdf