Which prisoners will be released?

Shortly after Hamas won a substantial majority in the Palestinian Legislative Council (PLC) 2006 election, Israel arrested over 30 members of the PLC. Those arrested were primarily Hamas representatives and they are still being detained as political prisoners in Israel. Evidently Israel and the US thought that they would be able to deny Hamas a majority in the PLC and that the more compliant Fatah faction would retain control.
The strategy did not quite work out as planned. Hamas promptly boycotted the PLC, preventing a quorum and the PLC has not functioned since. President Mahmoud Abbas (Abu Mazen) responded by appointing a caretaker government led by Salam Fayad. Hamas considers this government illegitimate since it has not received the PLC vote of confidence required by the Palestinian Basic Law. Hamas also considers President Abbas an illegitimate President as it takes the position that his term expired on January 9, 2009.
Since Israel and Hamas declared unilateral ceasefires ending the Gaza war, there have been ongoing negotiations between Israel and Hamas on a more permanent long term ceasefire. One of the points of contention has been the release of prisoners. Israel wants the release of captured Israeli soldier Gilad Shalit and Hamas wants over 1000 Palestinian prisoners to be released by Israel. This prisoner exchange will likely happen at some point. Israel has long been reluctant to release prisoners with “blood on their hands”, but since the Hamas PLC members are political prisoners they will probably be among those released.
This event will have a significant impact on the political dynamic in the region. The PLC will be reconstituted and will probably remove Prime Minister Fayad from office and install a Hamas led government. They probably will also begin proceedings to remove Abbas from office. These steps could result in new elections.
Since the Gaza war Hamas’ popularity has increased and polls indicate that they would win any new election. The US and Israel would then be faced with a Palestinian Authority completely under the control of Hamas. Things in the Middle East don’t always work out the way you plan. As Egyptian President Gamel Nasser once told an American friend “The genius of you Americans is that you don’t have simple stupid policies. You only have really complicated stupid policies.”