This is a big deal. "Open-ended" is the key phrase here, an indication that the Central Bank is prepared to keep buying bonds indefinitely in an effort to boost a sluggish recovery. It's also ready to do other stuff, if necessary. The Fed also announced that it expects short-term interest rates to remain near zero until at least mid-2015. From the NYT:
The Fed had given unusually clear indications in recent weeks that it was ready to act. An account of its last meeting, published in mid-August, suggested action was imminent unless the economy showed "substantial and sustainable" improvement. A few weeks later, Mr. Bernanke spoke of his "grave concern" about the high rate of unemployment and said that in his judgment, the likely benefits of additional action outweighed the potential costs. A number of longtime observers of the central bank said they could not recall a Fed chairman using stronger language. Since then, the economy has shown little evidence of substantial improvement.