@jeff mentioned on the Bombcast he had it figured out about 2/3 through the game. I had similar thing myself, but a bit later on. Specifically when you and Elizabeth finally come face to face with Comstock in the garden and he eludes you know something about her finger and why she wears that thimble. I figured Booker was Columbia's previous Songbird and perhaps he'd pecked her finger off (lol), I couldn't put the pieces together but it was something along the lines of that.

Did anyone else have any other theories which fell by the wayside as the twist began to unravel?

P.S. I'd love to see the Bomb Crew do a Spoilercast of Infinite, if only to hear Jeff's theory.

I would also love a good spoiler cast on this ending, or some kind of developer interview / commentary on it.

the ending honestly took me by surprise. i thought that cage/bird necklace thing was gonna come into it somehow and turn out to be some ridiculous quantum moment where if you chose one then it changed a bunch of stuff, but I guess that is dumb. i'm glad it didn't end on a boss fight, and that the toughest enemy was the handyman because the fight at the end of bioshock 2 wasn't enjoyable, and in general boss fights in FPS games are bad.

and yeah this has to be one of the most story-driven and "zeitgeist-y" games of recent times, I'd be kinda bummed out if they don't do a spoilercast at this point

I figured out the twist before it was revealed. Which kind of sucks, because the impact of that last moment would've been way crazier. But I guess I feel good for being smart and all. I don't know, this game is fucking awesome.