This background was taken from wiki, it is accurate and is a good place to start this post.

Sunni Muslims, often referred to as Ahl as-Sunnah wa’l-Jamā‘h or Ahl as-Sunnah, are the largest denomination of Islam.

The word Sunni comes from the word sunnah, which means the teachings and actions or examples of the Islamic prophet, Muhammad. Therefore, the term “Sunni” refers to those who follow or maintain the sunnah of the prophet Muhammad. Another etymology proposed by some[who?] is that the word “sunni” comes from a movement “Am-ul-sunnah” started by Mu’awiya.

The Sunni believe that Muhammad did not specifically appoint a successor to lead the Muslim ummah (community) before his death, and after an initial period of confusion, a group of his most prominent companions gathered and elected Abu Bakr Siddique—Muhammad’s close friend and a father-in-law—as the first caliph of Islam. Sunni Muslims regard the first four caliphs—Abu Bakr, `Umar ibn al-Khattāb, Uthman Ibn Affan and Ali ibn Abu Talib—as “al-Khulafā’ur-Rāshidūn” or “The Rightly Guided Caliphs.” Sunnis also believe that the position of caliph may be democratically-chosen, but after the Rashidun, the position turned into a hereditary dynastic rule. After the fall of the Ottoman Empire in 1923, there has never been another as widely-recognized caliph in the Muslim world.

Shia Islam (Arabic: شيعة‎ Shī‘ah, sometimes Shi’a or Shi’ite), is the second-largest denomination of Islam. Shia Muslims—though a minority in the Muslim world—constitute the majority of the populations in Azerbaijan, Bahrain and Iran, as well as a plurality in Iraq, Kuwait, and Lebanon.

In addition to believing in the authority of the Qur’an and teachings of the Muhammad, Shia believe that his family—the Ahl al-Bayt (the People of the House), including his descendants known as Imams—have special spiritual and political rule over the community[3] and believe that Ali ibn Abi Talib, Muhammad’s cousin and son-in-law, was the first of these Imams and was the rightful successor to Muhammad, and thus reject the legitimacy of the first three Rashidun caliphs.[4]

The use of a female suicide bomber in Iraq by the Sunni against the majority Shia (backed by Iran) during a high religious pilgrimage is not unique, the press is covering this as if this was the first time a female suicide bomber has been used. Females have been used over the past 20 years, the first was in Lebanon by secular members of the Syrian Socialist Nationalist Party in Southern Lebanon. It is impossible to pretend that Hezbollah had nothing to do with this given their operational control over that area in the 1980’s. They have occurred also in India, the Tamil Tigers used female suicide bombers to murder Prime Minister Ghandi. They have been used in Chechnya, Turkey (by the PPK), in Israel by the al-Aqsa Martyrs Brigade, and by Abu Musab al-Zarqawi’s al Qaeda in Iraq. I do see a pattern here, the Iranian funding and training of these groups; that makes this aspect of suicide bombing primarily a Shia operation.

The advantages of using females is that they do not fit into the terrorist ‘profile’ and are often overlooked by security professionals. Modesty is also a factor, women are not searched, or even looked at in Muslim countries as thoroughly as men; women are often allowed to pass freely through the checkpoints. Combine this with a hajib, burqa, and the niqab and what you have is a concealed, invisible smart bomb.  ABC reported “last week alleged that American law-enforcement officials have been told to be on the lookout for female suicide bombers who may attempt to enter the United States. The network quoted one official saying that at least two such women are believed to be connected to Al Qaeda in Yemen and may have a non-Arab appearance and be traveling on Western passports.” The terrorists will never stop, they will continue to find ways to attack us.  Be prepared, In my opinion the next attack will have nothing to do with airplanes. All of the airport/airplane probes are a ruse to keep our attention away from other, now much easier to hit, targets. We can’t watch all of the malls, restaurants, schools, or other soft targets.

If women are used more frequently this means that the masculine chauvinistic Muslim ideals of jihad, martyrdom, and free pass to paradise and its rewards is not holding in the face of increased anti-terrorism efforts and more aggressive searches and profiles. The next step for the terrorists is that once the women are searched and countered, children will be used as suicide bombers next.