Well written and very interesting. I totally agree with your thoughts on the shell. As a matter of fact I am thinking of doing a shell integration from a UI experiment of mine and might very well consider using your attempt as a base.
Your work with libnoise seems really interesting as well as readline gets in the way when you are trying to build really small systems.
So based on this it seems that your tarot project is interesting as well. I will try to take a look at it as soon as I have time, which might be a while!!