[Wilya]

Zsh certainly does something like this.

Here's what my autocompletion looks like: http://leukensis.org/files/zsh-autocomplete.png

The program has to provide its autocomplete files, but it's very powerful. My 'kill' autocompletes with a ps-like output, for example.

[samsquire]

Does zsh support matching long and arguments? That's what I want. A bit like fish (http://fishshell.com/assets/img/screenshots/man_completions....) and finalterm which others have mentioned.