post-singularity evolution

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So let's assume a sort of "Ray Kurzweil" exponential growth of technology over the next couple hundred years. At some point, human intelligence merges with machine intelligence, and eventually the physical, biological human brain will become just excess weight. At this point, humanity as we know it may be on the road to extinction, outclassed in every way by a new species of unimaginably superior intelligence.

The question then is, what guides the evolution of this new species, and its own decendants? Obviously the concepts of mutation, competition, reproduction, selection, speciation etc. become radically altered for the new species, which is free to alter its own programming at will. Still, I somehow suspect there to be a logically simple principle or set of principles (analogous to what we call "evolution") that guide such a life form and "selects" certain dominant character traits -- the question is, can we prove that this is the case under very reasonable assumptions, discover what the principles will be, and even discover what the dominant character traits are likely to be, centuries or millenia in advance?