One of America's greatest but underutilized assets is former presidents. In the majority of countries in the world the only way leaders exit the stage is through death or a firing squad.
Perhaps their greatest value is on diplomatic missions outside the norm -- they have stature so their word is taken seriously, but they have no official standing so they can also be at arms length from the sitting president. If President Clinton had failed to get the journalists returned, it wouldn't reflect badly on President Obama.
From North Korea's perspective, they could release the two journalists under the guise of showing humanitarian concern but without appearing to cave into American pressure. But make no mistake -- they have sent a conciliatory signal to the Obama administration.
What happens next is the key. Does this open the door to serious negotiations over North Korea's nuclear program? Or is this merely North Korea's attempt to buy some goodwill from President Obama while they continue in their inexorable march toward nuclear weapons? Will President Obama respond to the journalists' release by offering something in return?
Net-net, this is a plus for North Korea. They nabbed two American journalists to serve as bargaining chips. They've now played those chips. The next move is up to President Obama. If he rewards them for what is, in effect, taking hostages, it will only encourage North Korea to snatch another batch.