@Syne --
Quantum theory also only speaks on incredibly tiny scales, scales which are utterly useless on the scale that humans function on. By that point all of the various probabilities have cancelled out leaving only the most probable course, meaning that for all intents and purposes a large enough clump of matter would still act in ways which are predictable(hence why relativity still works on those and larger scales).
While we can't predict with absolute certainty how individual particles, say a proton, will respond to gravity, we can predict with certainty beyond any reasonable doubt how large groups of particles, say a human, will respond. In fact to date we have done so unfailingly, no group of particles large enough for the uncertainty principle not to apply has responded to gravity by falling up. In effect this means that quantum theory may indicate that a god can't necessarily predict which path an electron will take, but that he's still able to predict the movements, and thus the future, of large groups of particles.
Would there be room for error? Well that would depend on just how complete his knowledge is. If his knowledge is indeed maximal then there would be so little room for error as to be non-existent, if not then he is not omniscient and thus not a problem for proponents of free will(though there are plenty of other problems for them to contend with).
Of course the simplest solution is to just drop the god concept all together.
