Good stuff going on over there at CodeCombat. My favorite part about this headline is that during office hours PG questioned them about their decision to go open source, so I wasn't sure if they would do it. This shows me that CodeCombat has a vision they are following and I believe a big bright future.
I had a personal blog post about that story that someone posted to HN, and the top comment thread there was very helpful to us in the decision to open source anyway:
sillysaurus2 and highCs made some excellent points about ignoring what the gaming industry as a whole was doing, and this went a long way toward allaying our concerns. Then we talked to everyone we could think of who might have reasons why this wouldn't be a great idea, including some good lawyers, and no one could think of anything.
For a startup like CodeCombat where the audience may be interested in the code, open source should be the default choice, and hopefully we can succeed in this and start to make that happen by example.
http://www.youtube.com/watch?v=ABuvRv4Vv3s