It has been apparent since early March that the Democrat nominee will be decided by the super delegates because neither Obama or Clinton can reach the 2025 votes needed with pledged delegates alone.  Super delegates are free to throw their support to whomever they please but the point of primary elections is to determine and honor the "will of the  people".  A secondary consideration for the super delegates is to have a strong united party.  They have two choices: declare their support "starting now" or "let the process playout" until more primary results come in. In either case they do not want to be perceived as the one to overturn the will of the people and of course they want to promote goodwill within the party in order to form an effective coalition with the eventual nominee in the general election.

Given this premise, the super delegates are in a variation of the Prisoner's Dilemma in the role of the prisoner.  The dilemma, studied in the economics branch of game theory, is reference at Wikipedia:

Two suspects are arrested by the police. The police have insufficient evidence for a conviction, and, having separated both prisoners, visit each of them to offer the same deal: if one testifies for the prosecution against the other and the other remains silent, the betrayer goes free and the silent accomplice receives the full 10-year sentence. If both remain silent, both prisoners are sentenced to only six months in jail for a minor charge. If each betrays the other, each receives a five-year sentence. Each prisoner must make the choice of whether to betray the other or to remain silent. Each one is assured that the other would not know about the betrayal before the end of the investigation. How should the prisoners act?

A prisoner, acting solely for their own self interest, in this situation should snitch and avoid the worst possible sentence of 10 years.  The best action is for both to stay silent but this is only possible if they can somehow cooperate for the sake of their mutual interest.

The undeclared super delegates are similarly situated as the prisoners and their action can be guided by translating the prisoner payoffs to the relevant political objectives.  The two choices are declare now (stay silent in the Prisoner's Dilemma) or wait until later (betray).  The objectives for these choices are to not be perceived as the one to overturn the will of the people, ensuring the nominee does not become "damaged goods" for the general election and keeping the party united and strong.  For Clinton undeclared (prisoner A), the payoff for declaring now gives them political cover for not appearing to have been the one to overturn the will of the people because there are still undeclared super delegates and outstanding pledge delegates.  Waiting until later will make them appear to be the one to wrest the will of the people because it will be increasingly unlikely that Obama's lead in pledged delegates and qualified popular votes cannot be overcome.  For the Obama undeclared (prisoner B), the payoff for declaring now means the increased possibility of ending this already very long primary and thus promoting good feelings within the party.  Waiting until later will damage their candidate.  The reason is because Clinton needs to win each remaining contest by massive margins to overtake Obama's lead in the pledged delegate tally.  Because substantive differences between the candidates have already been offered, persuading voters to vote Clinton can only be achieved by shameless pandering and going negative on Obama.

Exploring the four different payoffs:  1) If they both wait later, Clinton supporters risk being perceived as the one to subvert the will of the people in addition to having conducted a very negative campaign.  Obama supporters risk making their candidate weak in the general election should he be the nominee.  The result is bitterness all through the party especially come January.  This is equivalent to the betray-betray action in Prisoner's Dilemma.  2) If Obama supporters act now and Clinton supporters wait till later, the former group can possibly put an end to this primary while the latter group will again run the risk of being perceived as the one to overturn the will of the people, tearing the party with unprecedented negativity.  3) If Clinton supporters act now and Obama supporters later, the former group will get their political cover but the negativity will continue in the effort to persuade the remaining pledged delegates and the still undeclared super delegates to vote Clinton.  4) If both act now, it gives Clinton supporters a chance to express their own will while not appearing to rape the electorate because there are still primary election ahead.  For Obama supporters, they can possibly put a merciful end to this primary and keep their candidate out of the muck.  Party unity is more likely because there is no need to go negative. This is equivalent to both prisoners staying silent.

Fortunately and unlike the Prisoner's Dilemma, cooperation is possible and acting now yields the highest payoff for individual super delegates and for the party as a whole.  Cooperation is simply heeding the urging of DNC chairman Howard Dean to declare their choice "starting now".  Senator Evan Bayh is promoting the worst payoff for all involved by discouraging those who wish to declare now.

PS- for the undecided undeclared there is nothing to be gained and everything to lose by waiting longer no matter who they end up supporting.