I don't remember seeing "Green Monday" deals before, but I looked it up and discovered that it's been around for a few years. See http://www.wisegeek.com/what-is-green-monday.htm
It has nothing to do with ecology, they're calling it "green" because it refers to the money retailers hope to take in on those days.
These are a few of the promotions:
Amazon - http://www.amazon.com/Green-Mo.....g=b0c55-20
Best Buy - http://www.bestbuy.com/site/gl.....ksdevice=c
Retailers are doing everything they can to get shoppers to spend more, with free shipping, early promotions, convenient ways to use mobile devices, and hard-to-beat online deals. Apparently Green Monday is the second Monday in December, a week after Cyber Monday (or Cyber Week, since those deals lasted all week). And, according to reports, the deals will spill over into tomorrow for Green Tuesday!
Then next up there's "Super Saturday," the Saturday before Christmas, on December 20th this year.