While I was surfing the internet I accidentally stumbled upon spoon.net.
The site offers free applications and games with some "streaming app. technology"

Apps and games aren't downloaded but "streamed" via your browser. It lets you play WoG like a real thing without installation.
Go and see it your yourself: spoon.net just click on World of Goo and wait for plugin to download.

Is that legal? Did 2D Boy actually approve??  ???  The game that people payed to play is now free online??
More cool games like Crayon Physics, Cogs are there.

This is bigger rip off then all those mini games that actually got approved by 2D Boy....

Looks suspicious to me. I guess it's to showcase their technology or something. Two concerns: one is privacy, and the second is whether or not they are really allowed to do so. I bet they did actually buy a copy of WoG, but with most other indie games you're "allowed to run it on computers that you own." Since the game is actually running on their server, that part is satisfied. The problem is that it's not allowed for public performance or something.

Is this the complete game ?
It could be only the demo, and in this case, 2D Boy may have allowed them to run it on their platform.