I doubt it. Just went for a quick browse. There are no big name programs in there yet. Porting the unity editor to HTML5 would be a huge undertaking, one that may well be impossible.
I for one hope nobody at UT wastes their time on it.
It seems like it’s just a thin client underneath, if I put my laptop in flight mode it instantly becomes unresponsive. If that’s the case then they wouldn’t need to port the whole editor, merely install it on their server and setup their systems to be able to run instances of it.