Try to view what YouTube listed until recently as its most discussed video of all time and you get this page:
The woman appearing on the poster frame for the number one spot, "Truth about Islam from an ex-muslim", appears to be Wafa Sultan, a Syrian-born psychiatrist who now lives in the U.S. She has spoken out against Islam, warning that "The clash we are witnessing around the world is [...] a clash between a mentality that belongs to the Middle Ages and another that belongs to the 21st century [...] It is a clash between freedom and oppression."; words that sound remarkably like the warnings one can find in the writings of another fugitive from Islam, Ayaan Hirsi Ali.
Of course, there has been no reply. The page listing the "most discussed videos of all time" is different now: the video in question was purged from the list about two days after I sent my email. This means that YouTube's list is a deliberate falsehood; the videos shown there are not in fact the most discussed, but rather the most discussed videos that have not been removed yet in response to Muslim demands.
And there can be little real doubt about what happened here. Muslim censorship of YouTube is not new. YouTube is now owned by Google, which has been famously cooperative (link dead now) with the Chinese government in censoring its search results returned to Chinese citizens. Perhaps those experiences have taught them that they can bow to demands for political censorship without risking their market share nor the embrace of the techno-literati.
I'm not going to maintain a list of all instances of self-censorship in response to complaints from Muslims or fear of a possible Islamic reaction, but this seems a convenient place to keep track of some of the less well-known incidents.
April, 2008: At a recent press conference, Christopher Hitchens relates that the Washington Post has refused to publish an article that it had asked Sam Harris to write on the subject of the reprinting of the Danish cartoons depicting the Muslim prophet. Their objection was that Harris referred to religious violence in the same sentence as the word "Islam".
An unsourced article (dead link now) on Digg claims that Muslims have organized to falsely tag videos critical of Islam on YouTube as violating the terms of service; and that YouTube responds by removing the videos.