As I've seen from the tutorials, QML seems the only way to create graphical apps in Ubuntu for tablets. Other languages seem to be only for using OpenGL, not Qt libraries.
My question can be rephrased as: Can I grab some Linux C code and compile it in Ubuntu for tablets?
We are encouraging the use of QML and HTML5, but if you want to make your C code compile across different hardware there isn't anything that should stop you.
Check out the following pages. They both contain an overview plus examples to get you started.
https://wiki.ubuntu.com/Touch/CoreApps/ has links to some more involved examples, shipped by default on the phone.
