This year is the 30th anniversary of the international day of peace.   Is this Lisa's dream?   Just speculating. 
http://en.wikipedia.org/wiki/International_Day_of_Peace

The only other days I see of significance are:  9/12/2011 which is the 3rd year anniversary of the Lehman brothers bank failure sparking off the financial collapse or the date of 9/11/2012.