Yes, sliding glass patio doors and French doors "placed into service" in 2009 and 2010 are eligible for the Federal tax credit as long as they meet the criteria. The tax credit is for 30% of the total cost, up to $1,500.
From January 1 - May 31, 2009 all ENERGY STAR qualified windows can qualify for the tax credit.
Beginning June 1, 2009, to qualify for the tax credit, windows (and doors and skylights) must have a U-factor and Solar Heat Gain Coefficient (SHGC) less than or equal to 0.30. This is a super effiicient window, and most ENERGY STAR windows will not qualify.
Save your receipts and the Manufacturer's Certification Statement for your taxes.