Siri is undoubtedly THE high-profile feature of the iPhone 4s (does S stand for Siri or not?). Before Siri, ‘voice interface’ meant basic text-to-speech and voice command implementation; now it means ‘personal assistant.'

We were barely getting over the pleasant surprise of discovering that Siri actually worked when the full scope of the implications started to dawn on us. Accessibility options for the variously impaired? Done. A less-distracting way to use devices while operating a vehicle? Of course.

Apple’s latest patent filing proves that the company has these bases covered, and more. Siri will be finding a home on “a number of different platforms, such as device APIs, the web, email, and the like, or any combination thereof.”

Are you getting it yet? The control interface is only part of the equation. Siri “provides a conversational interface that the user may find more intuitive and less burdensome than conventional graphical user interfaces...” In other words, Siri (and undoubtedly her as-yet-unborn children) will ultimately replace the keyboard and graphical user interface (GUI) paradigm that has driven desktop computing for several decades.

Multi-touch control has been (and will continue to be) a major evolutionary step for mobile devices. Despite the potential, and some notable inroads, the verdict is still out whether the multi-touch interface will find more mainstream adoption among fixed-installation environments (the server, the office desktop, the home theater, etc). If Siri’s children take off the way that Apple and others envision, multi-touch won’t get much of a chance.

In the evolution of the interface, Siri is to multi-touch what multi-touch was to the keyboard (or, more broadly speaking, any button-based hardware). No hands-on interface can compete with a truly sophisticated and ‘intelligent’ means of hands-free interaction.

We can’t ignore the other current ‘fork’ in interface evolution: gesture recognition. Consumers have embraced accelerometer-based controls such as the Wii and Kinect; all that remains is to remove the controls themselves. From eye-tracking to sign-language recognition, researchers and developers are doing their best to insert the user into a translatable 3D space -- and 2011 proved how close the consumer display world is to bringing 3D space into a mainstream experience.

But Siri is already ‘there,' in the sense that users have already embraced the voice interface; there are only refinements and extensions of the technology to look forward to, rather than any significant remaining technological or familiarity barriers to mainstream adoption. Until the day comes when the direct neural implant is a mature reality, it’s difficult to see where Siri (or Siri’s children) will be supplanted.

The not-too-distant future -- that half-virtual, three-dimensional Internet of Things -- requires a common means of interaction to ‘bind it all together.' The always-with-us, multi-talented personal assistant that is the smartphone seemed likely to provide the link... but Siri potentially transcends a connection to a single device; when integration between user interface and apps are already this seamless, how great of a step is integrating the user’s voice with every other uniquely-addressable item as well?

In the short term, we can easily envision Siri’s integration into appliances and vehicles -- helping us drive and do the laundry, for example. Turn the lights on and off, turn the heat up or down. Withdraw cash (Siri can even remember your pin number, so you won’t have to worry about covering up your button presses -- or dropping the card between the car door and the ATM). Not to mention Siri’s role as The Universal Translator. It’s not a matter of science fiction at this point, it’s simply a matter of version updates and third-party adoption.

In the long term, Siri’s integration will rely more and more on that final part of the equation: intelligence. As it is, we’ve seen impressive evidence of Siri’s ability to make personal recommendations, and to independently choose between available options in a way that is tailored to the individual user.

Consider the day when you get a Thank You note concerning that perfect personal gift that was received for an occasion that you completely forgot about in the first place -- because not only did Siri remember for you, but also took the initiative of coordinating with past histories, wish lists, online shopping apps and delivery services. Oh, and your bank account. Well, you’ll probably be notified before a Siri shopping spree. Probably.

Of course, in Siri’s current form, that would mean a lot more little bits uploaded and downloaded with each command -- let’s hope mobile bandwidth gets cheaper and more efficiently managed, or that Siri’s children are more robustly configured for ‘offline use.'