PlayUp Alpha ver. 0.9.2.621 is now available in the Download section. This version supports the ability to export levels from SketchUp into Unity. Since the scene files in Unity are kept in binary format, exporting to Unity requires the additional installation of the bundled Unity package in this zip file. Please help me convince the developers to make a text version of the scene files by voting in the feedback forums.
Note that if you export groups with the same name, the last one imported will write over the rest. Also exporting models with nested components or groups is not supported in this build.
VIDEO: Simple example of exporting from SketchUp to Unity 3D