Since their website is top notch I will not attempt to rehash the purpose of the project. Let us just say that it has a print head that can extrude plastic while moving in three dimensions. This allows it to build up layers of plastic into a 3D object that is accurate up to 0.1 mm (in theory).
I will begin building after a bit more research. Oh, here is a video of Adrian Bowyer talking to the economic and social impacts of a Replicating Rapid Prototyper: RepRap Pop!Cast