I was just reading a reason article suggesting that a major reason for this price spike is the dfalling value of the dollar. that is, because oil is traded in dollars and the global oil exporters do not want to see their revenues slashed because of the loss of dollar value, prices increase.
It goes on to talk more about speculators compounding this effect too, but the effects of speculation is something i do not understand
it also mentions geopolitical uncertainty, but this level of uncertainty has not increased at such a rate to account for all of the sudden change in oil prices
http://www.reason.com/news/show/125414.html