Since several months ago, just like the muslims like to burn atributes related to u.s.a, such as the star spangled banner, u.s presidents dolls, etc, qur'an burning has also been incited by the non-muslims.
Funnily, many "non-observing" muslims were also enraged by the burning acts.
Apart from having "Islam" printed in some muslims' id cards (incl. passport etc), have we really treated qur'an as it should be? Many muslims put qur'an in some notch, cavity, whatever they can find above their houses' doors, in order to repel the devil and evil spirits. Asked why, they simply stated "they/many people told/did so". Many muslims still deliberately and consciously conduct adultery, fornication, corruption, burglaries, money scam, and so on. Just exactly the same things forbidden in the qur'an, that committing them is taken as blasphemy towards God.
So why should many muslims be angry when some savages from so called modern industrial countries burn the qur'an...It is just a big insult done in one big (sometimes explicit) step. While the muslims themselves are regularly committing things deemed sinful in the qur'an, thus insulting the qur'an itself, by saying by deeds, not by words nor by fire, that it is not a holy refered book, since its contents is not observed and practiced anyway. Even practicing things contradictory to it.