What language are you going to make the standard within your GBJAM IDE?
I am using Haxe and Kha to make this engine, and so I'm using hscript ( a more limited version of Haxe ) for my IDE. This is mostly out of convenience. If I decide to keep working on this I may switch to a different language.
I have just uploaded my current progress to Github. There's still a lot of work that needs to be done.