This piece was initially inspired by the first chapter of Damien Broderick's The Spike: Accelerating into the Unimaginable Future, from our Reader. I found this idea of a barrier beyond which we can't see very interesting. If one was to take the long view of technological determinism (where the first catalyst was the stirrup, as you say) then this spike in computing power seems like the thing most likely to radically change the world's political structure away from capitalism and into something else. Whether or not it's actually any better (allowing more freedom, equality) is another question.
If the medieval church had no way (or didn't have the foresight) to stop the printing press, then perhaps this point where machines take on some form of sentience will be the same for this era.
Another influence on this piece was a little review I found at kuro5hin.org which explains a series of books written by Iain M Banks to do with an anarchic society called The Culture. The thing I borrowed from here was the idea of a giant spaceship that essentially was an artificial intelligence, with humans living within it.
With my piece I'm putting forward the idea that, on this ship (the Juggernaut) the people are relegated to the role of bacteria or white blood cells, while the ship constitutes mind and body. While antibodies are important, I'd hope that we have more of a role to play in the future than this.
While the Juggernaut's mind is is powerful and operating on all four levels at once (alpha, beta etc) its Achilles heel is that it needs the humans because (like us, at present) it cannot view its own mind with full objectivity in order to recreate it. Perhaps at some point beyond when this piece of story is set, the mind would progress further, but there has to be some balance.
I suppose that the other two possibilities are that humanity might intentionally create this artificial supra-intelligence, but (one would hope) that it would have goals that were harmonious with humanity's. Or that a domino effect (a real technological juggernaut) of one machine creating a more advanced one, which does the same again, until they build a successor that is sentient as well as well as intelligent. However, I don't think that this kind of machine would have much respect for we `biologicals'. I could only hope that in this situation the human illogic would beat machine logic.
This is what I call the `Captain Kirk' principle, where humans will throw their own lives into immense risk for the desire to save the life that is being risked (and other upstanding values, like freedom) and where the machine is `playing chess' in order to win and humans are `playing poker'. Perhaps this is being optimistic, but while it's conceivable that machines will speed past us in the area of intelligence, it's hard to imagine them replicating that `spark' displayed in people (like Palestinians willing to blow themselves up for their people's freedom) which from an outside perspective must look like insanity.
The game Go is mentioned because, at present, computers are hopelessly bad at it. I've never played it but have read that as a game its open-endedness makes chess look like accounting.
The possibility of becoming transhuman or cyborg is not really looked at in this piece. One cyberpunk world, Shadowrun, puts forth the idea that the more cybernetic implants a person acquires, the further from `natural' they become and the closer to insanity they get. I think this theory would sit well with the story.
However people have the ability to remodel themselves, but this also is generally done without consideration of possible psychological consequences or the allotment of time to adapt to drastic physical change of the self.
Like the human body, Juggernaut keeps as many redundant systems on hand as possible. Thus it recruits 80 humans to fill the role that could be done by one.