Time for action - using the free Autodesk FBX converter
There is now an easy way to convert SketchUp Collada (.dae) files to .fbx files. This has only just become possible with the 2012's release of the FBX converter. If you haven't done so already, download the Autodesk FBX converter from http://www.autodesk.com/fbx.
Export your SketchUp file as before, using the DAE format as shown next:
Open Autodesk FBX converter.
In the left-hand side box, click Add... and select your DAE file.
In the right-hand side box make sure Destination Format is set to FBX 2012.
Click on Change destination folder to set the destination to your game folder.
Now click on Convert. You can see the setup in the following image:
What just happened?
The newly-released 2012 version of the Autodesk FBX converter allows you to take Collada files from the Free version of SketchUp and convert them to Unity's native FBX format. This is an exciting development that many SketchUp and Unity users have been waiting for.