The new 2011 Roof Tax Credit extends to metal and asphalt roofs. The credit will cover 10% of your material costs up to $500. To be eligible, all materials must be Energy Star qualified.
This credit only applies to existing primary residences and can not be used for rental units, new constructions, etc.
Materials that qualify for the required Energy Star certifications typically are highly reflective or contain the appropriate colored pigments to reduce heat. Here is a PDF of the Energy Star Qualified Roof products.
This tax credit is very similar to the one offered in 2011 but has lower reimbursement rates. Click here to view a summary of the changes between 2010 and 2011.