There are conflicting reports about whether the IDF helicopter strike in Gaza killed Mohammed Deif. The IDF is saying that they got him (
report).
Update: Currently it looks like Deif was only injured but 2 Hamas fellows in the car with him were killed (
report).
Palestinians say that 40 bystanders were injured, including 15 children - but see
Imshin. 6 people were said to have been seriously injured. This wasn't the Shehade hit, but it wasn't exactly the Yihya Ayash hit either.
Here's a background article on Deif. He organized the Hamas "military" branch into a secretive and cell-oriented command structure, and had personal connections with Mohammed Dahlan that enabled him to stay out of jail even when the PA was doing its revolving-door terrorist roundups. Deif is an expert bombmaker, and is said to have had advance knowledge of all attacks conducted by Hamas from Gaza and given instructions and briefings in at least some cases.
Ynet (Hebrew link) adds that Deif planned the kidnapping of soldier Nachson Waxman and the murders of soldiers Aryeh Frankenthal and Shahar Simani. Israel repeatedly asked Arafat to incarcerate Deif; Arafat's customary response was to ask his assistants: "who is he?".
Hamas spiritual leader Abdel Aziz Rantisi seems a little dense. How does Rantisi react when Israel rockets a car carrying a senior terrorist leader and 2 other Hamas officers?
"We are determined to wipe out Zionist terrorism. They are targeting civilians. They are targeting children. There are at least 15 children among the wounded here," said Rantissi.