The State website reads:
Additionally, there will be a tax-free three-day weekend during which the sales and use tax will not apply to the sale of any Energy Star Product listed below, or solar water heater. This tax-free weekend will occur the weekend of February 18, 2012, through February 20, 2012.
Energy Star Product means an air conditioner, clothes washer or dryer, furnace, heat pump, standard size refrigerator, compact fluorescent light bulb, dehumidifier, or programmable thermostat that has been designated as meeting or exceeding the applicable Energy Star Efficiency requirements developed by the U.S. Environmental Protection Agency and the U.S. Department of Energy.
Maryland's next Tax Holiday -- "Shop Maryland Week" -- is August 14-20, 2012. Maryland rarely runs these, and didn't run one at all in 2009. So take advantage!