The Hamas/Fatah fighting isn't stopping the Qassams from being fired. At least 5 were shot today, one seriously injuring a woman and damaging her house in Sderot. Another hit a schoolyard.
It is probably Islamic Jihad's bid to unify the warring factions, since no matter which side you are on, they can always agree that shooting terror rockets at Jewish women and children is Allah's will.
(Our May Qassam calendar is here.)
UPDATE: Ma'an has a bulletin saying that Al Aqsa (Hamas) TV is saying that Hamas will launch "dozens" of rockets at Israel tonight.
UPDATE 2: Nine Qassams so far.
UPDATE 3: 18. 21 residents injured including 4 kids.
My guess is that Hamas is not trying to celebrate Naqba Day so much as they are trying to provoke an Israeli reaction that will stop the nascent civil war from escalating. Or perhaps they want to use this to solidify their leadership of Gaza.
UPDATE 4: Even during the Hamas/Fatah fighting, Hamas was publicly announcing the number of Israelis injured by their rockets - on the mosque loudspeakers.