Jeff Vail takes a crack:
[T]he only value added by the actual articulation of this new “Islamo-Fascism” label is falsity–it is the association in the public perception of attributes and attrocities of Nazi Fascists that are in fact not accurate when attributed to Salafi Jihadists. And it is in that sense that labels such as “Islamo-Fascism” are the purest of propaganda…
and from Alternet:
Italian Fascism, German Nazism and other European fascist movements of the 1920s and ’30s were nationalist and secular, closely allied with international capital and aimed at creating powerful, up-to-date, all-encompassing states. Some of the trappings might have been anti-modernist — Mussolini looked back to ancient Rome, the Nazis were fascinated by Nordic mythology and other Wagnerian folderol — but the basic thrust was modern, bureaucratic and rational. You wouldn’t find a fascist leader consulting the Bible to figure out how to organize the banking system or the penal code or the women’s fashion industry. Even its anti-Semitism was “scientific“… It presents the bewildering politics of the Muslim world as a simple matter of Us versus Them, with war to the end the only answer, as with Hitler.