Upon completing Dreams of Trespass, I though it would be interesting to see what information I could find about Harems used as a form of protection, not for sex, and if there were still Harems like this that exist today.
Unfortanuatly I could not find anything specifically adressing the type of Harem that Fatima Mernissi lived in, but I did find information about this specifice type of harem. According to the Lexicon Orient, some of these harems do still exist, in places like Saudia Arabia, and household harems were a place for women to live, and in pre-islamic times, wives and concubines live together in the same house.
There was also a very informative artical on Wikipedia that gives the background and history of harems. The name "harem" itself literally means "something kept safe." Originating in Turkey, ancient harems could house hundrands, up to thousands of women at once for safe keeping. Some went willingly into these harems and others were forced their against their will.