Anyone looking to use Sketchup as their CAD software (like me) should go to the Phlatboyz website and download their awesome Phlatscript plugin. You need to signup to their website but it is free to do so. The plugin converts your Sketchup geometry to g-code. They also have several tutorial videos on using the script.
I have not used the The Phlatscript plugin yet but was informed by Boort that it is great for cutting and drilling basic shapes in 2D but if you want to do 3D carving, you will need another plugin to convert the Sketchup native format (.skp) to DXF or STL format. You can download a free plugin from guitar-list.com that will convert SKP to DXF or STL. Once converted to DXF or STL, you then use your CAM software, such as CamBam or Vectric Cut3D to convert to g-code.
Another option for a Sketchup workflow, if you turned your Model A router into a rapid-prototyper (Rep-Rap like 3D printer) with an add-on extrusion head, is to slice your geometry first and then export to DXF or STL format. The free SliceModeler plugin (available from Sketchucation.com) for Sketchup can slice your model up quite nicely for "printing" in 3D. You could also use SliceModeler to make individual slices of a 3D model, let's say a head, and then while still in Sketchup, arrange the slices flat like you were making a cutlist diagram (i.e. laying them out flat on a sheet of plywood) and then use the Phlatscript to export to g-code and use your router to cut the pieces out of sheet material. You could then assemble the pieces one on top of the other up from the bottom in order to recreate the 3D head sort of like those "sliced" 3D puzzles that were popular for a while (click here for an example)
Anyrate, I love Sketchup so I intend to use it for my CAD wherever possible. I'll let you know how it goes. I hope this information proves useful.