I learned about him when I came to graduate school, as the University of Wisconsin has a student group, Dialogue International, inspired by his focus on dialogue and education as two necessities in the modern world. I've often been surprised, however, when Arabs I talk to claim to have never heard of it. Apparently they simply aren't active there:
"You are right, the Gülen movement in not active in the Arab world. One of the key reasons is that some Arab countries do not allow the movement to operate and treat it as an agent of the United States (or even an agent of the CIA, since Gülen lives in the United States). It is also viewed as an agent of globalization. The Arab world is not at all sympathetic to this movement.
"Also, Gülen and people around him do not necessarily want to get involved in the Arab world, because they believe that it does not understand Islam properly. In fact, they want to distance themselves from the Arab world. Here you have the nationalist aspect of the movement coming to the fore."
Anyway, those interested in modern Islam would do well to check them out, as their network of schools alone will make them influential in the 21st century.
(Crossposted to American Footprints.)