in reply to Different "states" in a my own Shell

Copyrighted and patented, eh? Just so you know, if you haven't ACTUALLY patented it yet, I don't think you will be able patent it in the future, since you've just published it :)

I don't know anything on CPAN that specifically applies to your scenario, but you might want to look at the programs Katapult (for KDE) and Quicksilver (for OS X). They're not shell replacements, but they do the handy search-plugin thing really well (especially Quicksilver). Browsing over the code for Katapult (which is open source) may give you some ideas.