repl.it co-creator here. Yes its powered by the repl.it open-source project but more features will be built on top of it and would be integrated with other codecademy products. I just joined codecademy and I'm particularly excited about how much it would help advance repl.it as an open source project.
Right now you could load modules from the stdlib. At some point we will add the ability to upload custom modules to our servers and require in your code.
