The Prisoner's Dilemma is different, since (here) there is no punishment if there is no betrayal, and betrayal is basically atomic.

No, it's the same. If no one talks, nothing bad happens. If one person talks they get to keep all the money and everyone else eats a big fine.

Look at the matrix in [1]. The matrix here is

    +-----------+
    | A,A | C,B |
    +-----------+
    | B,C | n/a |
    +-----------+

With (A=B) > C

[1] http://en.wikipedia.org/wiki/Prisoner%27s_dilemma#Generalize...