My guess is that Bill Clinton would not have gotten involved if he didn't have some assurances that there was at least a chance of being successful at bringing American quasi-journalists Laura Ling and Euna Lee home. I certainly hope he facilitates their freedom. It strikes me that this isn't a bad kind of thing for former presidents to do. They have a certain cachet, and being out of office they have a certain freedom of movement and action that serving presidents simply don't. That doesn't imply automatic applause for everything an ex might do -- Jimmy Carter has sometimes been an embarrassment, and it's hard to imagine Dubya being much of an international negotiator.
I hope the incident -- even though Bill will probably downplay it during active negotiations -- will bring more attention to North Korea's incredibly brutal hard-labor camps, described in this WaPo piece and to which Ling and Lee were sentenced. Not many people emerge alive from them.