Our current power grids are dumb.
They are great examples of 20th-century technology, but they are going to get much better.

We have the technology, today, to make our power grid more sustainable, cleaner, more robust and more reliable just by replacing old-fashioned metering with "smart-metering"[1] and agreeing to pay enterprising power consumers for generating some of their own electricity.
Today, almost all our electricity is distributed from power plants through the "power grid" to users. The electricity only flows one way. The utility generates the power. The power flows through wires to homes and businesses. The homes and businesses use the power. The utility measures how much power is used, and charges the customer.

The new, smarter grid, allows every power customer to become a power generator as well as a power consumer. The consumer and the utility are "interconnected." "Smart meters" measure the power flowing both directions and compensates the customers for their contribution to the power supply.
Where "net metering" is available, utilities measure the customer's "net" usage. If you can generate some of your own electricity – with photovoltaics, wind or any other generator – the utility buys it from you and sells it to other customers nearby. When we distribute electricity across long distances, some of the power is lost in the process. About 6 percent of the power generated in the United States is lost to transmission inefficiencies.[2] If we empower individuals to produce their own power – and pay them for it – the electricity is distributed more efficiently because it doesn't have to travel as far.
The utility customer gets compensated for the power, the utility gets a new, inexpensive power source and the grid becomes more reliable and efficient.
Our old-fashioned grid is unnecessarily vulnerable to weather and incompetence. When things go wrong, homes and businesses can go without power for days or weeks. On a hot afternoon in August, 2003, a technician in Ohio forgot to re-start a computer program after a routine procedure, then maintenance problems shut down a nearby power plant and some power lines sagged into trees in Walton Hills and Parma, Ohio. Within hours, 55 million people in the U.S. and Canada were without power.[3] Every year hundreds of thousands of North Americans experience temporary power outages due to weather. Scientists in 2005 estimated that power outages cost the United States about $80 billion a year, on average.[4]

The principal method for preventing outages is to produce surplus electricity so that peak demand doesn't stress the system. That's costly, both for the utility and for the environment, unless that electricity is being generated by millions of individuals and businesses using clean, renewable energy sources. The utility can acquire that power at an attractive price, and it doesn't have to plow billions of dollars into new generation facilities.

Net metering and smart meters are spreading. Most of the United States have laws that authorize net metering and part of the grid was open to net metering in at least 35 states at the time of this writing[5]. Unfortunately, implementation of net metering and smart meters has been relatively slow. Consumer demand may accelerate the process in the near future, and consumers will probably drive new pricing negotiations with the utilities, as well.

Imagine a power grid that includes millions of individual generators – photovoltaic panels, wind turbines, big coal plants, natural gas co-generators, etc. – interconnected with smart meters, paying on a "net-metered" basis and supporting each other.  In mid-summer, when North American demand for electricity peaks, the photovoltaics are also generating more electricity. When overgrown trees interrupt the power supply from a coal plant in Ohio, a wind farm in Pennsylvania takes up some of the slack.

Photovoltaics and wind energy were pioneered by independent spirits who wanted to live "off the grid." The most negative aspect of an off-the-grid system is the necessity of storing electricity in batteries – an expensive, toxic and inefficient technology. Interconnection with the smart grid allows individuals and businesses to benefit from generating their own power without the necessity of storing it in batteries.

And our supply of electricity – whether or not we generate it ourselves – becomes more reliable and secure as the big industrial generators are supplemented by thousands – or millions – of small independent producers.
Unfortunately, so far utilities have hampered efforts to implement net metering on a large scale. Most of the United States limit the amount of power an independent generator can sell to the grid, even where net metering is available. In most places, consumers are pushing their utilities and governments to liberate the utility grid, so it can get smarter.

[1] Declan Butler. Energy efficiency: Super savers: Meters to manage the future. NATURE: International Weekly Journal of Science. February 8, 2007. http://www.nature.com/nature/journal/v445/n7128/full/445586a.html. Sourced March 31, 2010.
[2] U.S. Energy Information Administration Office of Coal, Nuclear, Electric and Alternate Fuels. State Electricity Profiles 2008. March 2010. U.S. Department of Energy, Washington DC 20585. DOE/EIA-0348(01)/2.
[3] U.S.-Canada Power System Outage Task Force. Final Report on the August 14, 2003 Blackout in the United States and Canada: Causes and Recommendations. Chapter 5. April 5, 2004.
[4] Allan Chen. Berkeley Lab Study Estimates $80 Billion Annual Cost of Power Interruptions. Research News/Berkeley Lab. Feb. 2, 2005. http://www.lbl.gov/Science-Articles/Archive/EETD-power-interruptions.html. Sourced March 31, 2010.
[5] U.S. Department of Energy Energy Efficiency & Renewable Energy. The Green Power Network: Green Power Markets; Net Metering Policies. http://apps3.eere.energy.gov/greenpower/markets/netmetering.shtml. Sourced April 1, 2010.