Scratch has been around for about 15 years now, and 12 years in a workable state. And while it seems superficially to be helpful (none of that fussy text editing!), I have never met a programmer who got their start in Scratch.
It was a real environment, people were doing real things, and I learned based on the (at the time, quite bad) example of professionals. It also made it easy to go on Wikipedia and directly transfer concepts into my program from the pseudocode or C. Learning first in a real language gave me the opportunity to read many real programs very quickly.
I think GoMix and, to a lesser extent, Cloud9 give you a real language environment. I think that's a good step, though I have some minor qualms about the quality of the integrated text editors (which is really the web's fault).
Forget career-ready, I want naturals to never need to be told or convinced to program.
Don't want to threadcrap too much, but I deeply believe that most programming in the future will happen in environments like GoMix, in the same way that a ton of programming today happens in Visual Basic.