TouchDevelop has been around for quite a while; I remember first installing it on my WP7 phone back in 2012. I'm very happy to see the editor open-sourced.

I think this is a great example of Microsoft's new-found desire to promote learning and openness, rather than fight against it as they did in the past. My opinion of them over the past few years has slowly been swinging towards positive, and even though I'll likely never give up on Slackware and OpenBSD on the desktop and the server, I'm happy to see this new vision bearing fruit.