Ever since The Ties That Bind aired there has been a lot of discussion about the possibility that Kara's painting on the wall of her quarters on the Demetrius could include hints of a Ship of Light from the O.G. Battlestar Galactica from 1978 that stared Lorne Greene as Adama and had Richard Hatch as Apollo.
io9 recently ran an article on the hidden clues recently in BSG as did the Contentquake's Battlestar Galactica blog.
And here's a discussion of it, on the Battlestar Blog on Live Journal posted by Matt.
But the earliest discussion I recall of this being a possible arc on the new BSG was presented by artist Grant Gould right after Maelstrom aired. As Grant noted at that time:
Mark my words: Kara is human. Special human, yes. But still human.
Clues as to what's going on are sprinkled throughout "Maelstrom," and I think the episode called "War of the Gods, Part 2" (from the original series) gives some huge hints as well. We know that RDM has paid homage to the original series several times in the past -- the biggest of which was probably the Pegasus storyline -- and I think we're gonna see some of that again.
In "War of the Gods, Part 2," the topic of humans who are special and have potential beyond normal humans is explored. There's a scene where Adama is sitting in his chambers using his mind to move a small golden statue of a bird (which looks very similar to the small golden statue of Aurora that Starbuck gave Adama in "Maelstrom"). Apollo walks in on him, says "WTF?" and Adama proceeds to tell him that years ago there were people who could train to realize their brain's full potential, mind over matter, etc. He said that some humans are in the early stages of being able to expand their minds, and it was something he'd been working on before the attack. (Who knew Papadama could use the Force?)
Later in the episode, Apollo and Starbuck are on an alien world and Apollo gets killed. Starbuck, along with another pilot named Sheba, hop in a ship to bring Apollo's body back to Galactica. Along the way, they encounter a big glowing crystal-like ship of lights (seen in the photo above). They're pulled toward it and go unconscious.
When they wake up, they're surrounded by crystals and light, as well as FIVE FIGURES wearing white (that look very much like the Final Five D'Anna saw in "Rapture"). Starbuck asks where they are, and one of the Five tells them that the city of light is not located in their world - it's in another dimension (between life and death). Apollo is brought back to life and he and Starbuck are told that they're special and have more potential than most humans, and that the reason the Five are helping them is because they share a common enemy, and because the humans are now as they once were. (Verbatim: "You are now as we once were.")
The heroes are then sent home and don't really remember any details.. However, they suddenly realize that somehow they all now know the coordinates to Earth. The Five somehow embedded the knowledge into their minds.
There are several hints in "Maelstrom" that make me think this is the direction we're heading.
The oracle seemed to call Starbuck "Aurora" as soon as she walked in the room... We heard the name Aurora several times, in fact. Aurora = Goddess of the Dawn. Dawn = Light. I know that's kind of cryptic, but it seems to foreshadow events in a big way, along with the fact that the lighting in this episode was a major player -- Lights going out around Starbuck, then one light illuminating her face.
Starbuck's last words to Lee were something like "You have to let me go, they're waiting for me" and her face was lit by a blinding light. She was seeing something - approaching something - some beings. "THEY are waiting for me."
Leoben wasn't exactly Leoben -- he said as much in the episode. Perhaps Leoben was one of these Beings of Light, one of the Final Five, an angel or guide of some kind to help her along. He even tells her that her destiny lies somewhere between life and death..
Conclusion: I believe that Starbuck is going to awaken in the presence of the Final Five (or Beings of Light, whatever you wanna call them) and I think they're gonna give her the roadmap to Earth.
Remember, Grant wrote the above the night Maelstrom aired over a year ago. So far, in many ways Kara's arc this season mirrors Grant's rather prescient observations.
Patrick R. Aquilone wrote a detailed essay on his Starbuck Theory for Slice of Sci-Fi that is similar to Grant's take, but also factors in the hybrid's prophesy from Razor.
So, will we actually see Ships of Light on Battlestar Galactica along the way to Earth? Maybe. Maybe not. But, all of this has happened before... some of it even happened in 1979.
In other theory news... Dukeblack revised and added further detail to his observations of the constellation of Orion seen in the background of The Ties That Bind.
Shane Coffey of Cellounge and Radii at Galactica Variants post alternate decodings of the Last Supper image and propose alternate characters as the final Cylon.
While I enjoy exploring theories, I think it's easy to get lost in the weeds. I would suggest that in thinking these things through Occam's razor should be the guide post.
It'll be interesting to see if any of these theories play out in season 4. What the writers actually have in mind remains a mystery, thankfully.