The fragments are known collectively as the Cairo Genizah (or Geniza) from the Hebrew for a document-store. Nearly a third of the materials are scattered around the world in universities and research institutes; the remaining two thirds are in Cambridge.The article gives several examples of the importance of the Geniza texts (light shed on the work of Maimonides, the text of the Jerusalem Talmud, etc.). There are also important early fragments of some of the the Hekhalot documents which clarify their original text and there are lots of magical amulets, recipes, and handbooks that vastly increase our knowledge of early Jewish magic.
Now, documents in all locations are being scanned and catalogued and within five years should be available to the world via the web, thanks to an initiative launched in 1999 by the Friedberg Geniza Project, an international foundation. The main player in the project is the Taylor-Schechter Genizah Research Unit (widely called the Geniza Unit), set up in the mid-1970s to manage the Cambridge collection.
The importance to Jewish studies research of this online archive is expected to be revolutionary. The Geniza is “the greatest single hoard of primary sources for the study of Judaism and Jewish history ever uncovered,” says the University of Manchester professor Philip Alexander. The Dead Sea Scrolls, he argues, “have gained huge publicity because they are earlier in date and because they throw light on the origins of Christianity.” But the Cairo documents “are much larger in bulk and more varied in content, and they illuminate the ‘mainline’ rather than a sectarian ‘branchline’ of Judaism — Christianity.”
Background on the digitization project is here and here.