Has anyone come up with an easy way to take a Sketchup model and convert it so that it can be run on a cnc machine without having to manually recreate everything in another piece of software?

Not that I know of. But I know some guys that are converting Sketchup to STL, and then sending that to a 3D printer. There a free SU to STL converter out there. CB.

Not at all. SketchUp is a surface modeler, most every software that I've used that transfers to CNC (for timber) is solids based, and there is no easy way to get the surfaces to come in as solids. Adding joinery makes it even messier.

And then you'd need to have the software know what to do with joinery. HSB, Cadworks, and Deitrichs all have CNC modules that translate their joinery to tool language.