I'm just starting a thread for discussion about the simple on-screen keyboard currently under development. I wrote a review of the Gnome On-screen Keyboard (GOK) some time ago, pointing out some of it's usability flaws.
In an attempt to address these we have started a a python-based version that has a primary goal of being simple and functional first, and then add features as plug-ins later as needed.
I'd be interested to hear from those who have used on-screen keyboards, which features are important and your experience of existing systems. The main contributor to the project at the moment is Chris Jones, under the Google Summer of Code scheme. Please help him with encouragement, feedback and patches
Our current working plan can be seen here: https://wiki.ubuntu.com/Accessibility/Specs/SOK