From KGS Nightwatch:
Israel-Iran-Hamas: A member of Hamas' political bureau in Gaza City said that Hamas will not be a part of a war between Israel and Iran. The member said the group would not launch rockets into Israel at Tehran's request in response to a strike on its nuclear sites.
Comment: This confirms the report of a strategic shift in favor of Sunni Arab causes. Last week Hamas announced it would support the Sunni opposition in Syria. Today's announcement is consistent with that position. This is tonight's good news because it means Israel will not have to fight on three fronts - Gaza, southern Lebanon and against Syria-Iran. This is a setback for Iran.
Hamas was formed by the Muslim Brotherhood, and has always been a Salafist group. It was willing to spend Iranian money and pitch Iranian ordnance at Israel, and Iran didn't particularly care who did the shooting, as long as the Israelis were the targets, but in a Sunni/Shia infight, they're going to side with their own.