I doubt the apparently Turkish hackers broke into these accounts for the specific purpose of anti-Israeli defacement. The more likely scenario is they stole the account credentials by either phishing attack on Facebook (and, indeed, there was an Hebrew phishing attack on Facebook just last month) or by gathering the credentials of Israelis logging into Facebook by use of Trojan horses, such as those used for stealing bank login credentials.
Thus they are likely to already have had the user data ready for use in criminal activity, and then simply used it in this latest act of hacktivism.
Much like in the Estonian incident, in which the Russian-speaking population got engaged in attacking Estonia, those who know more on attacking computers, and those who already had resources to attack with (such as botnets) due to their existent illegal activities (such as spam), then joined the "party" and attacked, only using these more sophisticated tools rather than what the rest of the population was doing.
As researched in my soon-to-be-published paper with Dr. Robert Cialdini and Dr. Rosanna Guadagno about how the online Russian population was manipulated to attack Estonia -- whether on purpose or as an ad-hoc response to events -- the hackers in this case followed the social proof of so many people being active online, and spreading as a meme (social contagion) as a cue, and as new social norms emerged jumped on the bandwagon and launched their more sophisticated attacks.
This attack is special because it is the first active attack of Facebook accounts for the purpose of propaganda (that I know of), but it is in no way technologically innovative or shocking in concept.
Whenever there are political, ethnic, or religious tensions, the online aftermath follows in short order.
Then if the other side in this conflict has not yet attacked (whichever it may be), it gets upset by the attacks and responds in kind.
Truths to be remembered: