The same "perfect storm" that fucked the housing and credit market in the US is, according to Max Keiser-a wall street veteran and commentator, mutating and spreading to global commodities market. If that system blows up, expect the economic downturn to last much much longer.
Here's a video of Max Keiser explaining how this happened:
Some info on Max Keiser:
http://en.wikipedia.org/wiki/Max_Keiser
NOTE: I don't particularly get excited about the neo-marxist vocabulary he uses, however he does have a point regarding the globalization of off the balance sheet/'shadow' accounting inherent in commodities backed securities. If this winds down like the mortgage backed securities of the past... it's going to be VERY rough.