But now that we have more episodes behind us, I'm not sure. Kripke has been consistent in saying he won't string the audience along forever (cough cough... Lost, ahem). He says he's wrapping up one story arc this season.

I don't know what the twist will be, but from reading the episode summaries, I think Kripke was either talking about the episode that follows Folsom Prison Blues (won't spoil it if you haven't seen the summary), or it will be the return of John Winchester - in some form or another.