Free As In Speech
The designs of the RepRap are open source (under the GPL) so everyone is free to build one, modify the design and redistribute built RepRaps with the design. This means you are free to build your own RepRap with just the cost of the materials needed and your time to assemble the device. On the RepRap website it is stated that one could build a RepRap for about $500 in raw materials and build the rest of the required parts with another RepRap, I’ve looked around and so far I came out at about €700 to order the parts and have them delivered. (Mind you, this would be an electronics and a full mechanical kit). But at a material cost of €400-€700 this device is not out of reach for the general public, assembling is probably a bigger hurdle for most. I am myself still not sure whether I will be able to assemble one, even though I am quite convinced I want to try.
Self Replicating
One of the goals with the RepRap project is to be able to create all the parts for a new RepRap with a RepRap, currently this is not possible because it can only use one material but a lot of parts can already be created. The first working RepRap created earlier this year and was demonstrated at OSCON (which I unfortunately missed ). One of the purposes replication is to allow everyone with a RepRap machine to cheaply make more of them available.

A New Industrial Revolution?
Currently goods are mostly mass produced in factories and shipped around the world. The RepRap (well future versions mostly) will allow everyone to produce quite some items just at home. You buy raw materials (printer cartridge), and print some new item. Currently you can only print small items made out of 1 material, for examples see this page. But what if you could print your next mobile phone? This would mean there would be less goods to manufacture and ship around the world and could have enormous impact. The revolution would be a shift from centralized manufacturing to personal manufacturing.

Environmental Impact
A shift from central to personal manufacturing could reduce transportation and packaging impacts on the environment, but there are a few more benefits. The plastics used in the RepRap are biodegradable in a compost heap at 60 degrees Celcius, quite warm but not impossible. So this means old items created by the RepRap can be disposed of without harming the environment too much. The goal is to be able to reuse old or incorrectly created parts later on which would obviously be even better.

Sources

• The RepRap Project Site
• The Official RepRap Store - Sells electronic kits for a RepRap
• Bits From Bytes - A RepRap parts store
• RepRap Blog