If your looking for a free open source easy to use SketchUp to Gcode generator please take time to look at SketchUcam
http://www.openbuilds.com/resources/sketchucam.1/

We use it all the time here at the shop for making simple 2.5D designs straight from SketchUp to our control software. Since the .cnc files are text files you can usually just rename the extention to what ever your machine prefers. Be sure to look though the help file to find out all the hidden features and context menus for more control over the gcode creation.

It's been around for years and works very well. Also has and active community around it between OpenBuilds and the Phlatforum
Hope this helps
Mark C

Nice one kwok thank you!
Mark and Trish

The Phlatscript can do it
http://www.phlatforum.com

There is a Shopbot to Gcode converter out there, but what really needs to happen is we would like to be able to do all the pocketing and archs and fold lines( not cut all the way through) right in sketchup.
Mark

I really hope that someone can make this happen!