One thing that hasn't been mentioned here is that the "Israel attacked the WTC" meme is extremely common in Pakistan (and to a lesser extent, Indonesia and other Muslim countries) - especially among the younger, more radical Muslim scholars.
Many of the young men marching in the streets of Islamabad and Jakarta believe this (according to TV interviews), and despite denials by the older ulamas, apparently this is being taught as gospel in some of the smaller provincial Islamic schools. All those protesters aren't marching because they think Americans should die - more worrying, they're marching because they sincerely believe that Israel has successfully duped the US government into declaring war on Islam.
Apparently, Arabs in the Palestine area also believe that Israel is behind the September 11 attacks - the Syrian Defense Minister, Mustafa Tlass has expressed exactly this opinion, that Mossad was behind the attacks and that thousands of Jewish employees had been told not to go to work that day.
According to the Jerusalem Post, Iran, Lebanon, and (ironically) Kuwait were some other Arab countries where this view was prevalent.
Personal opinion: This propaganda isn't aimed at you, the American public. This is aimed at swaying the rest of the Muslim world to the Taliban's side, the ones who only have one news channel, or the ones who don't have TV, but go to read their lessons at the mosque every day.
Sources:
Star TV Focus Asia interview, Sunday night, October 21, 2001 broadcast.
Jerusalem Post, Friday October 19, 2001 (http://www.jpost.com/Editions/2001/10/19/News/News.36550.html)