Are there any specifics you're looking for in a brochure creation tutorial?
I ask because there a multitude of ways to make a brochure. from a double sided rack card to 4-panel, gate-fold brochures and even bound booklets.
I make such items on a regular basis and would be able to write a tutorial on creating such items. Such a tutorial would most likely be application agnostic. Scribus specific instructions would be included whenever possible of course (this is the Scribus wiki after all). I would even be able to provide templates for such layouts, granted they would be little more than pre-sized pages with crop and fold marks - leaving the content creation to the end user.
Let me know what you think.