NB: sort-of-spoilers follow.
The whole point of the last kingdom in the Primer, and of the Drummers, was that although machine intelligence could outperform the human brain in certain areas - for instance, calculations involving very large numbers, or repetitive activity - there are some problems that the brain was inherently better at.
As one character puts it, quite nicely:
"As far as the laws of probability, my lady, these cannot be broken, any more than any other mathematical principle. But laws of physics and mathematics are like a coordinate system that runs only in one dimension. Perhaps there is another dimension perpendicular to it, invisible to those laws of physics, describing the same things with different rules, and those rules are written in our hearts, in a deep place where we cannot go and read them except in our dreams."
This points to the belief that there is some sort of mechanism in the brain that cannot be duplicated by any computing technology that we know today. A computer may simulate creativity or imagination, but in the end its responses are invariably limited. Of course, this is not to say that that simulation cannot come close to real creativity. The Primer would be a good example of this, if Stephenson had not implied that it was somehow linked to Hackworth (exactly how linked is debatable - whether Hackworth spent some of his time with the Drummers guiding the storyline of Nell's primer, whether the entire storyline was pre-determined, or whether the storyline was entirely created by the native intelligence of the book itself.)
The society of the Drummers was an interesting attempt to couple the best of both worlds: to utilise the creative and intuitive powers of the human brain in conjunction with the calculating abilities of nanocomputers to form a massive parallel computer with the power to create. The same character who spoke the quote above proposed to use the system's intuitive abilities to break the encryption used by the world-wide media network (think FreeNet).
This book will be of special interest to anyone familiar with the fundamentals of computing, as many of those concepts are integrated into the Primer. For instance, Nell's dialogue with the supposed Duke of Turing is a good example of a Turing Test, and Turing Machines feature throughout the book, albeit lightly. Stephenson also has some interesting ideas about nanotechnology. Like Snow Crash, Stephenson uses ideas that could be expanded to fill half a book by themself in almost a throwaway manner.
Bonus points for spotting the Snow Crash reference about two thirds of the way through the book...