One thing that is not mentioned enough is that any time the price per barrel is above $20, the OPEC countries make money. At the current rates, it is believes that these countries will have accumulated something in the neighbourhood of $15 Trillion petro dollars by 2018, and they will be looking to invest that somewhere - from a Canadian Business article:

There are certainly new fears about the rise of sovereign wealth funds. According to the Institute for the Analysis of Global Security, at the end of 2007 these funds had some $3 trillion in assets, but that will balloon within a decade to $15 trillion, an amount roughly equal to projected American GDP. Source

Scary.