Oh, another thought about that scene--this episode actually gives us two examples of Dean changing deeply-ingrained, long-held behavior: that confession to Sam, and the rock-paper-scissors match. In the latter, Dean's change in behavior brought him victory, which gives me great hope that his change in behavior in the former will also bring him (and therefore Sam) victory.

...Or I could be reading too much into a merely glorious bit of comedy. :P