Ponoko is a very cool on-line laser cutter fabrication service with a wide range of available materials. The idea is that you create a EPS file for the laser cutter to follow, specify the material, and they cut out the pieces and ship them to you. The laser can also engrave lines on the material. EPS files can be generated with Adobe Illustrator or various other similar 2D artwork programs. If you want to make a 3D project (like this table), you make it out of 2D pieces that fit together with slots and grooves. When you upload your EPS file and choice of materials, they figure out how much the laser cutting fee will cost.
Toby Borland (of SMARTlab in the U.K.) has designed a set of laser-cut plywood RepRap parts and made the EPS files available on the Ponoko website. There is a Flickr photo set showing laser-cut RepRap parts and the process of assembling them; I am not sure that's the same Ponoko files and process, or another laser-cutting effort, but it gives you a sense of what's involved, and the level of complexity.