On February 17, 2009, President Obama signed a stimulus bill (The American Recovery and Reinvestment Act of 2009) that made some significant changes to the energy efficiency tax credits. Tax credits for qualified energy efficient home improvements are available in 2009 and 2010 for 30% of the cost, up to a combined $1,500.

The products that are covered by the tax credit in 2009 & 2010 include:

Insulation
Windows (including storm windows)
Skylights
Doors (including patio & sliding glass)
Roofs (metal & asphalt)
Central air conditioners
Air source heat pumps
Geo-thermal heat pumps
Gas, Oil, or Propane Furnace or Hot Water Boiler
Advanced Main Air Circulating Fans
Biomass stoves
Water Heaters (Gas, Oil or Propane, Electric Heat Pump, and Solar Water Heaters)
Photovoltaic Systems (solar panels)
Fuel Cells
Wind Generators