After investigating the whole day Google Sketchup, finally, I want to suggest this to be added to the list.

http://www.sketchup.com/?dlc=1

There are two version: the free version and the professional version, which is quiet expensive (~600 Euro). The disadvantage of the free version compared to the pro edition is the lack of exporters except the Google Earth format.

Suprisingly, I found today a free software which is able to read this format and is able to convert it to several other formats: Media Machines Flux Studio

http://www.mediamachines.com/make.php

If you convert it to 3DS, X or whatever you like you can edit it in your favorite 3D modeller or take it as reference shape in WED to rebuild it "from scratch".

This is really great! You can create whole interiors and house in minutes with just a few clicks. *gasp*