In metaphysics, libertarianism is the view that human beings (and other free beings) are free because they can do otherwise. Determinism is the view that the conjunction of the laws of nature with all the facts about the configuration of the world at some time t entail all the facts about the configuration of the world at all times. Compatibilism is the view that free will and determinism are logically compatible, and incompatibilism is the view that they are not. Libertarianism is generally taken to entail incompatibilism, and is contrasted with compatibilist theories of free will. However, in her recent paper "The Non-Governing Conception of Laws of Nature" (in Philosophy and Phenomenological Research 61), Helen Beebee points out that Humean supervenience theories of the laws of nature seem able to be deterministic without contradicting libertarianism: according to Humean supervenience theories, laws are purely descriptive, they don't actually make anything happen. The laws of nature will include future facts, since they are summaries of everything that happens in the world, but they won't make things happen that way. This seems to make it metaphysically possible for me to do otherwise, even if the laws are in fact deterministic. It still won't be physically possible for me to do otherwise, but this isn't because the laws of physics prevent me from acting - the laws of physics don't do anything, other than describe - rather, it's because if I had done otherwise, the laws would have been different.
Note that if God exists and has middle knowledge, he will still be able to ensure, among other things, that the fundamental laws of physics are simple, mathematically formulable, finitely axiomizable, etc. Alternatively, if Lewis's plurality of worlds exists, there will still be some "well-behaved" worlds where the laws have these properties.
Of course, Humean supervenience theorists can't explain why the universe exhibits regularity, but nomic realists can't explain why there are laws and why the laws are as they are, so they aren't doing much better. Besides, theists can explain why the universe exhibits regularity, regardless of their theory of lawhood.
Another interesting point here is that Humean supervenience will require that there be facts (in the present) about what human beings will do in the future (otherwise laws that quantified over all time would lack truth values). This has its own problems for free will. On the whole, however, a very interesting (and, in my view, quite possible correct) idea.