The Crusades have always been seen an an important event from the Christian/European side of the conflict. It seems like they were involved in the formation of the ideas of 'Christendom' and of 'Europe', and they've always loomed large in European history, whether they were viewed as heroic adventures, imperialist invasions, or just groups of hoodlums run amok.
Are they seen as a major event on the Islamic side? Were they always seen that way? It seems like they could have been dwarfed in Islamic history by the invasions of the Mongols and Turks, internal infighting, and other wars on other borders. Relative to the size of the Islamic world, the Crusaders could have been seen as a bit of a side show.
Is the 'importance' of the Crusades inflated in Europe? And, possibly, inflated elsewhere by the subsequent spread of European culture and therefore their version of history?
It seems like I'm asking a question of degree (I'm sure the Muslim world didn't forget the Crusades, after all...), so let rephrase the question: an average educated Westerner would have a pretty good idea when and where the Crusades were, what they were about, etc. That would also have been true in, say, 1800. Would the same be true for an educated Muslim, both now and in 1800 (ie. before exposure to 'Western history')?
They were absolutely a side show in comparison with the mongols. The crusades did not feature as a major concern for the Seljuks who were much more oriented towards the east. Saladin, who is the most famous Muslim combatant in the crusades, spent as much if not more of his time in battle against fellow Muslims.
Then "rediscovery" of the crusades had less to do with encounters with western history than in encounters with western imperialism where the history of the crusades was seen to show a direct parallel in anti-imperialist histories, essays, propaganda etc. The religious aspects in particular have influence with Islamist groups, who will today refer to pro-western Arab states and Israel as "crusader states."