I guess the phrase “open source” has taken on a meaning more than simply what the phrase implies. Unreal Engine is not open in the same sense the jMonkeyEngine is.
I personally would like to see all source code distributed with the binaries, under the same licence as the binaries. Imagine being able to fix bugs in “closed source” software, and distribute binary patches.
Also, Sweethome3D is pretty cool actually 
Its actually exactly what I need right now for my project so its really funny this thread came up.