For the next step I'll be focusing on fixing bugs, refactoring code, adding some features and improving the documentation.
Some of the things you'll find in my TODO list are:
Add polar interpolation in animations.
Mantain Child ordering during transitions.
Change node diameters based on the first dataset object value.
Graph support (trees with cycles...)
For the ST:
Performance improvements (bind with the Animation object).
Support for IE.
Bug fix (node diameters, multilevel display).
Graph support, (although it might be supporting Graph structures already).
Bug fix (mostly on computing rectangles dimensions).
Before adding some radical features (binding visualizations with real time mutable data, etc.) I really want to have a strong API, and in order to do that, I must do some research on my own.
Don't forget you have some quick tutorialsonthevisualizations. Also, the Hypertree, ST, RGraph and Treemap have some object references. Finally, there's a Google Group about the JIT here.