The Congress passed the Judiciary Act of 1789, which elaborated and specified the judicial powers:
http://usinfo.state.gov/usa/infousa/facts/democrac/8.htm
They actually did a bad job of putting the specific powers of the judiciary into the Constitution. But this act shows clearly that appellate review of questions of constitutionality was one such power, no?
I am glad to know that review was not "unilaterally" declared. Even so, I am going to have to read and digest that last sentence, also, for a while.