I've seen a few old (Gen2) threads on this subject, but I think the Plug-in Prius makes this relevant again, because now there's access to the power... Does the accessibility of the J1772 connector make it feasible to connect an off-the-shelf inverter to a PiP and get power, *without* modifying the car in any way? Or is there some built-in safeguard against that?
You cannot get AC power out of the J1772. You can do the same as other Prius cars, which is that you can attach a 12V, 1,000 watt inverter to the 12V battery and get AC power as long as the car is in Ready mode.
Or, if you have the skills, you can tap the HV directly and use a high power UPS (~3kw) as was done in 2006: PriUPS-getting electricity FROM your hybrid vehicle JeffD
The problem with pulling power directly from the traction battery is that it's high DC voltage. Getting a basic 12vdc to 120vac inverter isn't difficult or expensive (well, it's $300~$400), and it provides about 1,000 watts.