In short, Stacksmith is a HyperCard clone that runs on the current version of Mac OS X.
Make sure you've inited all the submodules, and then just build the Stacksmith Xcode project.
I'm still thinking about a license to open source this under. Some of the code used in Stacksmith is under the zlib license, but I'm not sure I want to be that liberal with Stacksmith proper.
Right now, consider all of this copyrighted and non-distributable until I've made a decision.
I'm open to well-reasoned suggestions, though.