All about the yen
It has the scent of coordinated central bank intervention (or at least Bank of Japan intervention) all over it, though we just don't know for sure. News leaked late yesterday that the BOJ might cut its interest rate target to 0.25% from the current 0.5% as well. That added some gasoline to the buck's rally.
All of this precedes today's U.S. Fed meeting on interest rates. Policymakers are widely expected to cut the federal funds rate by 50 basis points to 1% -- the same 1% policy rate that got us into the housing mess in the first place. There is an outside chance the Fed goes 75 basis points, but I'm not banking on it.