Ambient occlusion is one of the latest updates from the SketchUp team, an essential tool for those how use SketchUp to create their final 3D imagery to showcase their design ideas to their clients .

Check out the difference between using just the shadows tool vs using shadow+occlusion in this simple example:

It maybe subtle but I encourage everyone to try it out together with better textures then the ones using in the example it a big improvement for your 3D renderings.