I have heard of this. I am a member of an African American hair care message board where we were discussing this product. From what I gather, this "straightener" is very similiar to a relaxer, which is what we use to straighten our hair. It's a chemical that breaks down the bond of "curl", permanently straightening it.
You can buy home relaxers anywhere from $5 - $10. At the salon, the price is probably $75 to $100.
This product sounds like the same thing to me only more expensive.
Given the diverse textures of black hair that relaxers can be used on (from kinky to naturally straight) I don't see why you couldn't use it.