There's no question about it, Pan. Assuming that they are like every other political entity ever known to mankind, they will do what they can to stay in office and reap the benefits that come from such power. In and of itself that is not unusual, nor is it surprising. But the fact that they blew into office on the promises of making life better for the Palestinians-- backed by actual demonstrations of what they promised, ie good education for children of both sexes, fixing homes in disrepair from repeated airsrikes and bulldozers, lowering the crime rate in portions of Palestine that they are in control of, and listening and responding effectively to their constituency, they have set the bar quite high-- which, to tell the truth, wasn't difficult when considering the vast billions Arafat stole from his own people for his own personal use.
In short, they (Hamas) are locked in by the good behavior that swept them into power. Any backsliding into suicide bombings will have a direct negative impact on the everyday life of the normal Palestinian who just wants to live his life peacefully, thus insuring that Hamas deal honestly with Israel.
This is not to say that they will bluster and posture like the Hamas of old, but the actual behavior will absolutely be modified to the new reality of political power. The Palestinian in the street will allow Hamas to say all the militant and reactionary things that they always have (and in fact might be severely disappointed if they didn't!) as long as it does not actually impact their lives in a negative way. After all, tweaking the Israeli's noses is a way of life there on the Gaza Strip. Seeing the Jews get all riled up feeds the collective ego of the Palestinian nation, but smug satisfaction places a distant second to going to work on a daily basis, knowing the streets are safe, having well educated children who have good future prospects, et al.
Both Israel and the West may not see the silver lining that this election has, but I believe Hamas being in power is nothing but good news. Eventually everyone will come to realize that cold hard reality makes pragmatists of us all.
Totem