[weswood]

Depends on the kind of generator you get. Small portable ones that run on gasoline, you unplug the appliance you're going to use from the wall and plug it into the generator. You can also wire it directly into the breakers, but you need to be sure to turn off the main breaker. If the power comes back on while your genny is running and the main breaker is on, you can blow the transformer, or cause a fire in your house.

There's also larger permanently mounted ones that run on natural gas or propane. These are hardwired into your breakerbox and have a sensor that automatically starts them, usually about 10 seconds after the power goes out. When the sensor sense power coming from the grid, it shuts the genny off and reverts to grid power. They run around $8k to 10k and can run the whole house.

The neighbors around my house are the band together in an emergency type. We've gone 3 weeks without power after hurricane Ike. No gunfights or anything. One neighbor even cleared the fallen branches from my yard, knowing I was working 16 hour days getting the grid back up.