Acrobat 3D and SketchUp
The answer is Yes, we do support 3D SketchUp files in Acrobat 3D! There is a little trick though. You have to export the 3D Sketchup model as a .obj file. Then you can simply drag and drop the .obj into Acrobat 3D. This will give you a 3D pdf that you can share with anyone including those with the Free Adobe Reader. You may be interested to know that other Adobe products support SketchUp files.
As part of the CS3 release, we released Photoshop Extended which supports 3D models. At the end of May, we announced a Plug-In that supports Google's 3D warehouse. So if you are an avid 3D Google user, then I think you have all of your bases covered.
Have fun,
Jonathan