trystan830 posted this major spoiler of "Croation" in her LJ and I couldn't resist to read it.
At the end of the next ep. Dean is going to tell Sam about the secret that John told him before he died:
"Dad said that I have to keep you safe..that nothing else mattered.. cause if I didn't I'd have to kill you."
Wow, that's really something I didn't expect. What do you think?