The QE 3 announced by Fed was offered as an stimulus to housing market. But, it was translated as equivalent as an uncoordinated undervaluation of dollar. Uncoordinated mean that if other Central Banks actions that QE3 can be neutralized.
In Brazil, it feeds our fear of real valuation and of raising current accounts deficits.
But, for some countries the income effect can balance the exchange rate effect. In other words, an US recovery means raising imports even with a weak dollar.
The American proposal has only one target: housing market. For that, issue new money with mortgage as collateral has no linkage with basic interest rate or even with undervaluation. The development of financial markets allows Central Banks to act with discretionary in the short run with low impact on prices in the long run. Despite this, we have more efficiency in domestic monetary policy, coordination between countries is desirable. The Fed recent choice can be translated by rational expectations of an devaluation and reactions by other Central Banks to avoid worst current accounts. Dollar devaluation can induce new business with local currencies. If countries change their reserves composition we can think of externalities network or chain: diminishing demand for dollar currency.
A weak dollar feeds expectations of a new international financial architecture and prophecies for a new currency as a collateral of a basket of national currencies to prophecies of a regional use of internationalized currencies.
* I apologize for the mistakes in English! Corrections are desired!