Video of explosion and possible rupture at BP's oil-spill cleanup site:
Note: Some specualtion as to whether what we're seeing here is the result of the robot camera backing away and panning up, with the debris falling from the camera itself. Possible, but towards the end of the vid you see the debris moving fairly decisively towards and past the camera lens (a bit like a tv space-ship moving through an asteroid field), which suggests its being propelled from the leak.
PS. The best explanation of why this may not be an explosion/rupture is here. And, oh, by the way, BP's 2nd attempt to plug the well has officially failed.