A living text is one that attracts and becomes surrounded with living activity. Societies of humans annotate them, discuss them, even live by their ideas. The Qur'an, the Bible, etc. are living texts par excellence. Some would say they're too alive.
The web provides collaborative tools that can create the structure upon which a living text can thrive, thereby "leveling the field" for more numerous and diverse texts to come alive.
Content management systems can be specialized into collaborative, or social, book annotation systems.