Comment Not such a loophole. (Score 2, Informative) 775
IANAL, nor a Constitutional scholar, but "any Thing in the Constitution or Laws of any State to the Contrary notwithstanding" appears on its face to refer to State constitutions and laws, not to the US Constitution. The law citations I've seen on various sites support this view. According to the Supreme Court in Reid v. Covert, (http://en.wikipedia.org/wiki/Reid_v._Covert), "this Court has regularly and uniformly recognized the supremacy of the Constitution over a treaty".
Sooo: No, Virginia, treaties cannot serve as an end-run around the Constitution. If I understand the citations correctly, a treaty has status coequal with Federal laws passed by Congress, so a treaty could, for example, supersede a Federal law such as the DMCA; however, it could not do anything (within the US) that Congress couldn't do by legislative means, like overruling an Amendment to the Constitution.