Actually, taking into account that bitcoincharts isn't showing ANY activity <$4 I have a suspicion that it's not a wall at all, but rather the sum total of all holder who simply don't believe it will drop below $4.
Let's crash that bidwall! Come out person with 22000 coins. Send them to me and I will crash it then buy it back lower and give you the difference (plus I'll buy back some lower too with my own funds!)