Honestly from an AI perspective SC:BW and SC2 are probably more similar than from a human's perspective. 12+ unit selection, multi building selection & intelligent worker rallies aren't huge improvements for AI.
SC2 ticks way faster than SC1 though, which you don't notice much as a human, but you might change your strategy when designing the ai components.
Also I'd imagine the amount of time you spend making sure that units will path efficiently is way less!
But doesn't that just make the search space of possible moves per unit time larger? That would require more processing power, but it doesn't seem like it would necessarily change the fundamentals of how the AI works.