Nature Medicine has an editorial this month on global scientific leadership. (the link takes you to the abstract, the sum total of which is below; you might need a subscription to read the whole article, but try the Full Text link to see.)

"Some analysts believe that the economic hegemony of the US is on its last legs, but the same does not seem to be true of its scientific supremacy."

The bottom line: despite all the moaning and hand-wringing, the U.S. still leads the world in scientific research, and that includes comparisons to scientific heavyweights such as the U.K., China, and Japan.

This bottom line comes from a Rand study, "U.S. Competitiveness in Science and Technology" (downloadable as a free pdf.) The report and editorial note that while the U.S. leadership should not be taken for granted, the United States continues to lead the world in science and technology and has kept pace or grown faster than other nations.