I just had a new roof put on my house about a month ago and was wondering how to get the tax rebate for new shingles and roofing felt. Does the rebate include the labor costs or just the supplies?

You need to speak to an accountant on this one.
Just be sure you have all your paperwork to document what was done.
Perhaps the installer has forms for this as well. You may also try the manufactures web site for more information regarding what shingles they offer that has this rebate. Not all are covered in this program.