Shi;ite hackers kicking hell out of Sunni sites.
Shi'ite hackers may have been responsible for taking down over 1,000
Sunni ( al Qaeda ) terrorist sites. The Sinni hackers lack the knowledge to take
down Shi'ite sites, they can only deface them.
Sunni and Shi'ite Hackers Wage War in Cyberspace
The Sunni-Shi'ite cyberwar started in 2007 when a group of Sunni hackers calling itself "XP Group" threatened to attack all Shi'ite websites on the Internet, and proceeded to hack some 120 Shi'ite sites. At this point, representatives of the targeted sites, headed by Shi'ite sheikh Hassan Al-Saffar, filed a lawsuit in Saudi Arabia against a member of the XP Group named Na'if Al-Ghamdi. According to recent reports on Sunni forums, Al-Ghamdi has been arrested, and has disclosed the names of 17 other hackers operating in Arab countries. 
However, XP Group is not the only player in the arena. In May 2008, a group of Iranian hackers called "Ashiyane Digital Security Team" attacked the website of the UAE daily Al-Khaleej.
Sunni Hackers: Electronic Jihad Against the Shi'a Brings One Closer to Allah
In response to this incident, a number of Sunni hacker groups pledged to retaliate against Shi'ite sites. Among them were two groups called Shabab Al-Salafiyin and Al-Ayyoubiyoun. The latter declared on various forums that the war against Shi'ite sites was a form of jihad that brought one closer to Allah. The threats were realized in August 2008, when a group of Egyptian and Saudi hackers attacked the Shi'ite sites Fatimid Egypt, Egyptian Shi'a, and others. This prompted a Shi'ite group, Shabab Al-Shi'a, to threaten further attacks against Sunni sites. 
Shi'ite Cleric: The Hackers Will Not Silence the Shi'ite Voice
The cyberwar between the Sunnis and the Shi'ites intensified following statements by prominent Sunni sheikh Yousef Al-Qaradhawi in September 2008 against the spread of the Shi'a in Arab countries and against the Iranian regime, whom he accused of being behind this phenomenon.  The Sunni XP Group now hacked some 300 Shi'ite sites, including those of Ayatollah 'Ali Al-Sistani, the leading Shi'ite cleric in Iraq; prominent Saudi sheikh Hassan Al-Saffar; Ayatollah Muhammad 'Ali Taskhiri, secretary-general of the World Assembly for Proximity of Islamic Schools of Thought; and Ayatollah Sheikh Nasser Makarem Shirazi, one of the ayatollahs of Qom, Iran. The targeted sites were defaced with messages in Arabic maligning the Shi'ite faith and Shi'ite leaders. On Al-Sistani's site, the hackers also planted a satirical video deriding the sheikh.
Egyptian Columnist: Hacking Websites Is No Less a Crime than Murder or Arson
Egyptian columnist Diana Muqallid wrote about the cyberwar in the London daily Al-Sharq Al-Awsat: "It seems that the groups inciting sectarian [hatred] in our countries do not only blow up mosques and Shi'ite places of worship, and send out suicide [bombers as part of their] extremist war. The reciprocal killing in Iraq, the clashes in Lebanon, and the suspicion prevailing in many of the countries where Sunnis and Shi'ites live [side by side] are not enough for them - they must also [find other ways to] express their extremist sentiments, which are fueled by radical political views... Battles between Sunni and Shi'ite sites are being waged [on the Internet], with each side virtually killing and harming the other by targeting the websites of religious figures, political leaders, and media outlets such as www.alarabiya.net...
"Some still believe that hacking [sites] on the Internet is not a real or a serious [crime], but things are not so simple... Destroying a website or hacking it in order to keep people from entering it is [no less a crime than] murder, siege and arson. It is an act of negating the other. In our lifetimes, [we have seen] journalists murdered, incarcerated, tortured and exiled. Media outlets have been closed in our region or placed under supervision, [and their premises] have been burned down. Electronic attacks convey the very same sentiment of wanting to negate the other..."