| No, that's not the drain plug. The drain plug has a dab of blue paint on it, just to the left and below the power steering fan.
Try to look around the engine and make sure that it isn't oil leaking from further up and running down. At this end of the engine there is also the possibility that the oil fill cap is loose or that some oil was spilt when re-filling and is running down the back of the engine.
This is really just clutching at straws though, the location and the amount of oil really point to one of two problems, the oil pan gasket or the crankshaft oil seal. The oil pan (sump) gasket takes about 4 hours to replace (I have to change mine, it seems to be leaking in several places) and the oil seal will take much longer as the transmission and flywheel has to be removed. | 
