Yes, there is an adoption tax credit and for tax years 2010 and 2011 it was made refundable. Let me reassure you this is true. You may have to wait several months (5 months in our case) to receive your refund and you may have to do some work (phone calls and mailing documents), but if you are entitled to take the credit you will receive the refund. In our case, we finalized the adoption of our sons (3 biological brothers who were in our home as foster children) in 2007, but because we were able to carry-over the unused credit from previous tax years we were able to now claim it as a refund. Imagine our surprise!
I am attaching this post from Voice for Adoption which also has links to the exact IRS forms/instructions. Even if you adopted children from foster care and didn't spend any money on the adoption, you may still qualify. I would recommend consulting a tax advisor if you are unsure.