A change on the way?

From: The decline of the dollar
Currencies rise and fall over time because countries really do get richer and poorer. Dig something valuable up from under the ground, or devise products or services that people value, and your money will be worth more. Let your industries fall behind, or allow inflation to debase the value of your money, and its global standing will decline.
The puzzle is that there's no real evidence that the economic prospects of Western Europe have suddenly improved 40% compared with the U.S. This makes it tempting to assign the dollar's drop to the customary moodiness of currency markets, in which traders make guesses about the future and inevitably get things wrong for years on end.
There may be something more significant afoot this time, though. It has little to do with the economies of Europe (or of Canada, Australia or New Zealand, whose dollars have made big gains against the U.S. version). Instead, the real action involves the countries whose currencies haven't gained on the dollar despite dramatically improved economic prospects relative to those of the U.S.
China is the most obvious example. But there's also Saudi Arabia and its Persian Gulf neighbors, overflowing again with oil wealth. Even Japan, while not exactly booming, has seen its currency remain curiously weak during the dollar's long fall.
Why haven't these countries' currencies been gaining on the dollar? Because their governments won't let them. China's dollar peg, established in the mid-1990s, is often portrayed in the U.S. as a mercantilist attempt to sell more stuff here (if the Chinese yuan is cheap relative to the dollar, imports from China are cheaper too). But there's much more to it than that: by reining in the often pointless fluctuations of currency markets, countries can bring stability and encourage trade.
That's what the U.S. and the world's other big economies did during the 25 years after World War II. The Bretton Woods system, named after the New Hampshire resort town where the agreements were drawn up, brought unprecedented growth in global prosperity by bringing order to financial markets that depression and war had turned upside down.
But the very prosperity that Bretton Woods enabled was its undoing. As Germany and France returned to the ranks of major economic powers, and Japan began its climb to get there, the exchange rates set up after the war and adjusted only slightly afterward made no sense anymore. Attempts to update the system collapsed in 1971, and the world's major economies moved to freely floating currencies. The transition wasn't pretty: stock markets plummeted, banks failed, oil exporters jacked up prices and inflation raged--especially in the U.S.
These days, China and the other countries participating in what some have called Bretton Woods II export so much more to the U.S. than they import, they find themselves with hundreds of billions of dollars that they don't know what to do with. Up to now they've been content to recycle most of them by buying Treasury bills and other U.S. securities. The U.S. has enjoyed the low interest rates that have resulted, while China, the gulf states and Japan haven't wanted to face the consequence that by selling dollars, they would decrease the value of their remaining dollar holdings.
This is an arrangement that can't go on forever. It should unravel; that's the way of economic change and progress. But there's no plan in place to make it happen in an orderly fashion. The fear that the ensuing adjustment might be even more chaotic than in the 1970s probably explains most of the dollar's recent decline. It's not that we Americans have gotten a lot poorer. It's that we might be about to.