This is similar to something I've been wanting to do for quite some time. In contrast to your approach (binding JavaScriptCore at the Objective-C level) I want to start with the JavaScriptCore's command-line interpreter. It's currently a barebones interpreter. I would start by adding some missing primitives to the interpreter getting it closer to the V8 developer console (d8). Then work from there.

Good work though. It's nice to see that I'm not the only person that has thought about a Node-like system built on JSC rather than V8. I wonder if you looked at the source for both V8 and JSC, and then concluded JSC would be much nicer to work with? That's what I did initially.

I wish I had time to pitch in right now...