Information on energy efficient street lights was presented to the 'green team' at Cleveland City Hall in September, 2008.

“Effective energy-efficient street lighting uses a balance of proper energy-efficient technologies and design layout to meet performance, aesthetic and energy criteria required by pedestrians, motorists, community residents, municipalities and utilities.”
New York State Energy Research and Development Authority

“The most energy-efficient and highest quality option of standard street lights (in terms of light control, distribution and color rendition) is the Metal Halide Cutoff. Pulse-start metal halide lamps provide even greater energy-efficiency compared to standard metal halide.”
New York State Energy Research and Development Authority

The City of Ann Arbor is installing LED streetlights in order to reduce lighting costs and greenhouse gas emissions. After successfully piloting an LED replacement for the downtown “globe” lights (a retrofit of existing fixtures), the city received a $630,000 grant to fund retrofits for over 1,000 downtown lights. The initial installation will save the city over $100,000 per year, reducing annual greenhouse gas emissions by 267 tonnes CO2e. The eventual goal is to replace all of the city’s public lighting with LEDs.
City of Ann Arbor LED Summary

Cities that are piloting or using LEDs for street lighting include:

• Ann Arbor, Michigan
• Anchorage, Alaska
• Raleigh, North Carolina
• Austin, Texas
• Toronto, Ontario
• New York, New York

According to the Department of Energy, adoption of LED lighting in the United States can: Reduce electricity consumption by 62% Reduce carbon emissions by 258 million metric tons Eliminate the need for building 133 new power plants Lead to a financial savings in excess of $115 billion

Other options for energy-efficiency:

“Networked monitoring and control of streetlights isn’t restricted just to LED’s. Streetlight Intelligence, a publicly-held company traded on the Canadian TSX Venture Exchange (SLQ), offers the Lumen Streetlight Intelligent Management system (SIM) for computerized and networked control of HPS streetlights. According to Streetlight Intelligence the system delivers up to 50% energy savings, reduces maintenance costs by 25 to 40%, and eliminates up to 50% of greenhouse gas emissions.”
From - LED Streetlights: Innovation in Lighting the Night – Triplepundit.com

22% of the electricity consumed in the U.S. is used for lighting

LIGHT POLLUTION

In a breakthrough cooperative move toward the protection of dark skies, specifications calling for full shielding of solid state lighting (LED) luminaire street lights were included in the proposed criteria for the federal efficiency program Energy Star. If passed, the pending requirements, released on August 20, 2008 by the U.S. Department of Energy (DOE), will have a major impact on the design and marketability of all future LED street lights.
The International Dark Sky Association

Light Pollution Wastes incredible amounts of valuable natural resources. Hundreds of millions of barrels of oil... and hundreds of millions of tons of coal... just so people can light the bottoms of clouds?"
Light Pollution Pollutes the air we breath through needless generation of electricity (most of which comes from fossil fuels). See the previous comment about burning oil & coal. Air pollution is a serious problem that affects large segments of the population.

Light Pollution Harms nocturnal wildlife. Many species won't even go near an area that has bad lighting. Also, many species will simply stop reproducing if habitat destruction from overly bright lights becomes too severe.
From Starrynightlights.com – a website dedicated to providing information about light pollution