They called the operation "Drive Them Out," saying that they asked permission from Hamas to fire the rockets.
Their announcement bragged that they shot missiles towards "Jewish settlements" in the Negev.
If they are telling the truth, then this indicates that Hamas does cooperate with Sinai jihadist groups - implying at least indirect Hamas culpability towards the increasing number of attacks against Egyptian security forces in the Sinai. It also indicates that Sinai jihadist groups are freely operating in Gaza.
Meanwhile, at least one rocket was been fired from the Sinai towards the Israeli community of Bnei Netzarim in the past hour or two,according to AFP. No injuries or damage reported but the reaction from Egypt will be interesting.
(h/t Lachlan)
UPDATE: Jihadology counts that the MSC took credit for 38 rockets (h/t CHA).