I have been asked this similar question after telling people about my cleansing.
What is gallstone?
Everybody has gallstone?

I don’t have the book with me right now otherwise I will paste a few lines here. However I have found some answers from other Weblinks.

From http://digestive.niddk.nih.gov/ddiseases/pubs/gallstones/index.htm

Gallstones form when liquid stored in the gallbladder hardens into pieces of stone-like material. The liquid, called bile, is used to help the body digest fats. Bile is made in the liver, then stored in the gallbladder until the body needs to digest fat. At that time, the gallbladder contracts and pushes the bile into a tube—called the common bile duct—that carries it to the small intestine, where it helps with digestion.
Bile contains water, cholesterol, fats, bile salts, proteins, and bilirubin. Bile salts break up fat, and bilirubin gives bile and stool a yellowish color. If the liquid bile contains too much cholesterol, bile salts, or bilirubin, under certain conditions it can harden into stones.
The two types of gallstones are cholesterol stones and pigment stones. Cholesterol stones are usually yellow-green and are made primarily of hardened cholesterol. They account for about 80 percent of gallstones. Pigment stones are small, dark stones made of bilirubin. Gallstones can be as small as a grain of sand or as large as a golf ball. The gallbladder can develop just one large stone, hundreds of tiny stones, or almost any combination.
Gallstones can block the normal flow of bile if they lodge in any of the ducts that carry bile from the liver to the small intestine. That includes the hepatic ducts, which carry bile out of the liver; the cystic duct, which takes bile to and from the gallbladder; and the common bile duct, which takes bile from the cystic and hepatic ducts to the small intestine. Bile trapped in these ducts can cause inflammation in the gallbladder, the ducts, or, rarely, the liver.

Also from another source
http://www.relfe.com/gall_stone_cleanse.html

Removing gall stones may also help CONSTIIPATION, because it improves the flow of bile which is a natural laxative. 

Removing gall stones may also help to improve a body that is generally "run down".

HEPATITIS is an inflammatory process in the liver.  It can be caused by gall stones, because of the back-log of impure products.’’

What I have learnt is that Gallstones is a by-products of stress, imbalanced diet- too much protein / carbohydrate/ sweet, coffee, alcohol, improper sleeping pattern, improper eating habit, too little fiber, low fat diet and many more. That’s why it is quite fair to say that almost everyone has gallstones because of our demanding lifestyle.

The problems of Gallstones as it gets cumulated in Liver, gall bladder and various ducts are that it restricts the flow of bile, prevent toxic being cleared from these organs efficiently and provide a breeding ground for parasites. As a result, it weakens the function of these organs. Impaired Liver will cause various health problems especially those relating to the digestion systems. It depends on the person’s tolerance level; some will experience eye problems, diabetes, gout, high cholesterol, gut problem, constipations, arthritis, overweight, skin problem, and many more.

Some people might think that removing the Gall bladder would be a solution if Gallstones are found, even some medical research back this idea. But it is unnatural and it shows how ignorant we are to our own body. Without Gall bladder, bile will have no where to be stored but will be released constantly onto intestine as and when it is produced. The mechanism of control the release of bile is not there anymore and that will screw up the control when having low fat meal and high fat meal.

Although I believe Gallstones cause all these diseases, branding it as the Mother of all disease (like most of the books or articles about Gallstone) is probably too strong of a word to be used. To me, it is just one of the ways to spring clean your body and to maintain health. I believe in Balance and I believe each and every part of human body has its role to play. Any of the organ gets blocked / stuffed will have cascading effect on the rest of the body.