This looks pretty sweet. Use a free tool to create level designs. This would be cool if multiple games used the same standard format so your map/level could be imported into multiple games.

The concept's great, but the execution right now isn't even close.

The SketchUp plugins are very immature at the moment, and fail with most models that already exist in the Google warehouse – you have to be very careful with how you place and modify shapes in SketchUp to even get the model to import into Hammer, much less compile as a usable level, much less have it look as expected in the game engine.

As it stands right now, it's a much bigger boon for people who want to make simple props, as you don't need to learn 3DS/Maya/Blender just to get a chair or stool or box that you really want into the game. As for entire levels... not yet, but we're getting closer.