Both India and China are a significant reason for the steady rise over the last couple of years. China in particular is trying to build up their own strategic petroleum reserve and has more dollars then they know what to do with. So any time the price begins to sag, China starts buying more.
I wouldn't let the big oil companies off the hook though. While the current price is probably higher then they would like to see, it has become clear that during the late 90's and early 00's they intentionally set out to increase oil prices by reducing the over capacity of refineries in the US, despite the fact that oil demand was rising.
Jay