Forgive my ignorance, I don’t really know the difference between all the shader types. But do you think you can have a couple different demos… cell shading, and something else? Are you able to use freely available programs off the web, for example?
Sure, I can do that. I already have another demo idea in mind: using vertex programs to manipulate geometry in the scene. Not too complex, but it would encompass all the features of vertex programs in jME.
One problem: I won’t be able to work on it until the weekend. It’s yet another hectic week, so all I can guarantee is that the current work will be completed before Friday (hopefully before!).
Vertex programs have been committed for 0.6! All planned functionality is currently present, and it all works correctly. 
The code is also cleaned up and documented properly.
As for creating an additional demo, it won’t happen until next week at the earliest. I’m feeling sick as heck this weekend, so I can’t code much of anything in my Tylenol-induced stupor.
I’ll get the cell shader demo up on the demo page.
Rather than creating a new thread I thought I’d drag this one back to life:
I’ve made a small addition to the vertex program state. Now whenever a program is loaded, it is checked for errors. The line number and accompanying message are logged (level: SEVERE) if errors are discovered. Extremely useful for debugging purposes, I’ve noted.