I don't know exactly who released it, but buildwithchrome is now out! I remember sometime last year maybe? It was available, but in some strange quirk it was only available in Australia. You could build on plots of land on the Australian continent.
Well now it is available for everyone! And it is really cool. There is a build academy, which just seemed to be a tutorial, but quite a nice one, and there are blocks, and base plates, and different color blocks. Oh man, in short, it is great.
It does seem to have a limitation of only being able to share your work on Google+. I don't mind that because I use it all the time. Also, I am not sure you can save your builds if you don't finish them.
Regardless, I still like it.