The web isn't where a command line might shine though: it's Kwyno's support for commands sent via text and IM that make it intriguing: text in "Check Mashable", and Kwyno returns the latest Mashable headlines. Text "Check News" and get the latest headlines from CNN (or any news source you configure).
Kwyno will enter private beta in December, developer Raphael Caixeta tells Mashable. It may or may not be any good; and frankly, the concept is far more interesting than the execution...
YubNub, Where Art Thou?
Developed by lone coder Jonathan Aquino for the 2005 "Rails Day" programming contest, YubNub allows users to create shared commands for actions on the web: add "deli" to the front of a query to search social bookmarking site Delicious, add "flk" to search Flickr, type "gearth" to open up Google Earth and zoom to a location you provide. Better still: type the command "create" to create an entirely new command.
Twitter is Not The Answer
YubNub was, and still is, an idea ahead of its time.
A comprehensive platform for issuing commands and requesting data via short messages has yet to be built, and while you could send a command to the messaging service Twitter to request data (or issue the command "bedroom lights off", as shown above), it's not the kind of exchange you'd want posted to a public Twitter stream. Issuing commands via Twitter's Direct Message feature, meanwhile, is not only impractical, but puts you at risk of exposing those requests to followers.
In short: Twitter is not the command line you seek.
Mobile Penetration + APIs = Opportunity?