The Bank of Japan announced a 2% inflation target, open ended buys from January 2014 and additional steps. Most moves were expected. USD/JPY sells the fact:

The BOJ certainly caved to pressure coming from the new government led by Shinzo Abe. The LDP won a landslide victory and vowed to stimulate the economy. Elections for the upper house are held in July. The current coalition has a two thirds majority allowing it to bypass the upper house, but the LDP wants more power.
Dollar/yen traded around the critical 90 line and fell immediately after the announcement to 88.85, stabilizing above the 89.10 line afterwards.
Further support is at 88.40. A break above 90 seems somewhat unlikely now. For more lines, see the USDJPY forecast.