In St. Augustine's Confessions, he spends some time trying to imagine what the earth was like in Genesis 1:1, when it was "formless." His attempts center on the idea that formlessness is somehow between non-existence and form. Ultimately, he gives up on trying to picture formlessness, but I think he was on the right track for understanding it. Formlessness in the sense that it's used in Genesis (not the colloquial "formless" that means its form simply doesn't fit any pattern or shape we're familiar with) is, for all intents and purposes, nothingness. Form is a pattern of connectedness, a scheme that establishes relations between parts. Without relationship to anything, they might as well not exist. I'm reminded here of the "invisible, intangible unicorns in your garage" analogy that people sometimes use to disprove God. Essentially, the argument is that if you can't sense it or determine its existence in any way (and we would assume that in addition to being unable to be directly sensed, these unicorns don't scare cats or paint graffiti or do anything else to connect themselves to our world and thereby make their presence known), its existence is profoundly irrelevant. It might as well not exist. This is what is suggested by Genesis's statement that the world was dark -- inaccessible to our senses.

What God did in creating was not so much to bring something out of nothing, but to connect the formless "stuff" into form. Its existence became relevant because it could interact, it had relationships between parts. (I'm tempted here to make an analogy with electrons that can be understood only as fields of potentiality, until interaction with something else forces them to take on a definite position and motion -- but we've already established that my grasp of particle physics leaves a lot to be desired.)

I think the shift from "something from nothing" to "relevance out of irrelevance" makes God's act of creation more closely parallel what we know of creation since the Beginning. In art (for example), nobody ever creates something new, an idea out of nowhere. What true creativity consists in is making new connections. "Love is like a rose" is not creative, because it's a connection that's been made so many times it's become a cliche. But "Love is like an aardvark" is potentially much more creative, if it can be substantiated (otherwise the connection is uselessly weak).