During their research, they used water-repellent ferrous nanoparticles mixed in with the oil, in order to separate it later with magnets. The amazing part is that once the nanoparticles are magnetically removed from the oil, they can then be reused.

via MIT Develops a Way to Magnetically Separate Oil From Water | Inhabitat – Sustainable Design Innovation, Eco Architecture, Green Building.

Wait, can’t they then throw nanoparticles into an oil resevoir and then use a magnet to lift the oil without pumping?