Several defacement are part of coordinated efforts, while others are just individual expressions.
Hackers are mainly from Algeria, Morocco, Egypt, Turkey, Saudi Arabia.
There were also some coordinated efforts to launch a DDOS attacks on some Israeli governmental sites, the hackers used many forums to distribute the message, tools, date and time to launch the attack, I would assume that the bad performance of Internet in the Arab world due to the cables cut in the Mediterranean, largely reduced the effect of the DDOS.
Check the Arabic attack archive site: http://www.arabic-m.com for a list of hacked websites.
On the other side, Israel is making use of Internet channels like YouTube and Twitter to deliver their political messages, in addition to online monitoring service like http://israel.internet-haganah.com/
Israeli domain registration server (DomainTheNet) was hacked by a Moroccan hackers group, the hackers were able to get a password that allowed them to change the DNS records of some web pages to be forwarded to other pages with some political messages.
Israeli hackers developed a program and published it on the Internet attracting Israeli people to download the tool and contribute to the current cyber warfare between Israel and Palestine.
Analysis of the program was done by SANS, and it seems to be a risky one as it will try to connect to an irc server, and wait for orders, this can be used for many purposes.
The site is changing the location regularly, the last working address for it is http://help-israel-win.tk/
USA military sites are now part of the war, turkish hacker successfully defaced some USA military web sites and NATO Parliament site using SQL-Injection attacks.