Define innovative. One major goal of any shell is to get nasty shit done as fast as possible. Conventions accreted over time and breaking those too much diminishes the viability of an alternative project.
rush Ruby Shell [1] might qualify, but it has the problem of any "innovative" shell: different special syntax and doing something so different that the transition curve is too steep for most people.
Zsh is kind of weird because it feels academic with the option of having every feature imaginable AND not having hashes or signatures with releases. The good thing about zsh is that most of it isn't loaded by default. It has modules. It has lots of neat options lacking in other shells such as case-correction and interactive completion. That's all kinds of innovative.
Bash is the mysql of shells. It's pervasive so there's loads of pressure not to innovate.
I would like to see shells' community get more like node by having minimal, focused packages of added functionality that each do one thing well, because having to declare the same primitive functions to do something DRY and useful is a pain.
