There is already a reconciliation agreement between Abbas and Hamas, and this was already a factor in the release of Shalit. Whether Israel likes it or not (and official Israel still doesn't), Hamas will be involved behind the scened in the coming peacetalks between Israel and Abbas. Indeed, this is Hamas' long time position: They don't want to talk with Israel directly, and prefer that this be done by Abbas. Hamas will recognize a peace deal, but only if the Palestinian people will approve it. It will be wise for Israel to enable the peace process to proceed under such conditions, but Netanyahu may lack the wisdom to see it this way.
from the article: Peres: Israel stands with Gilad Shalit full of excitement