A couple of good paragraphs from Arnold Kling:
"Yesterday in my high school econ class, I found myself trying to explain why having a separate currency that could depreciate would enable the PIIGS to live happily ever after. I made the textbook argument, but I found myself not so convinced. OK, so maybe you can tell a story where one country that has a recession and a large fiscal deficit would be better off with devaluation. But there are so many countries in that position right now, and they cannot all devalue.
Speaking of "cannot all devalue," doesn't the impact of the PIIGS crisis completely nullify QE2? If the dollar appreciates 10 percent and the foreign sector is 10 percent of the economy, then that represents 1 percent disinflation, which probably more than wipes out any inflationary impact of the Fed's new bond buying program."