And God saw the light, that it was good: and God divided the light from the darkness. (ASV)
How does one separate light from darkness?
More seriously, it ought to be noted that the first Genesis creation story has an interesting schematic quality:
Enviroments: Day 1: Celestial: Daytime Nighttime Day 2: Far terrestrial: Sea Sky Day 3: Near terrestrial: Land Plants Inhabitants: Day 4: Celestial: Daytime: Sun Nighttime: Moon and stars Day 5: Far terrestial: Sea: Aquatic animals Sky: Flying animals Day 6: Near terrestrial Land: Land animals, humanity Plants: God says "you may eat these"
The second Genesis creation story has a different order: the first man (Adam), the animals, and the first woman (Eve). And unlike the highly-systematic first creation story, it is much more improvisational, with God fixing his creation as he goes.
Also, God seems very happy with what he has done in the first creation story, saying how good his creation was, and deciding to take a break after his six days of creative labor. But in the second creation story, God must find his creations rather annoying.
Shortly after the Big Bang, matter existed in plasma form. The free charged particles absorb and emit light easily, making it difficult for a ray of light to penetrate the plasma (consider the ridiculous amount of time it takes energy created in the center of the sun to travel to the sun's surface). When the universe cooled to the point at which atoms could be formed, light could travel without as much inhibition. Maybe this is the event hinted at by this passage, maybe not.
With regard to the latter objection, it seems that the first creation story is concerned with chronologically mapping out creation while the second is less a creation story and more a story about how the first woman was created. I'm not sure what the Hebrew implies, but the NIV version says, "Now the LORD God had formed out of the ground all the beasts of the field and all the birds of the air. He brought them to the man to see what he would name them; and whatever the man called each living creature, that was its name" (NIV, Gen 2:19). The word "had" makes it sound more like the story is going back to a previous event to cite necessary information for understanding the next event.
Finally, just because things are assembled in a more improvisational manner in the latter story doesn't mean the former is different. It could be that the former tries to condense events as much as possible while the latter describes them in more detail.