I spent almost all of the summer of 2007 working on a Flex-based brochure builder, or more accurately, a brochure editing application. The structure, however, is built ready for all the expected functions for a full publishing application on par with Microsoft Publisher. The benefit is obviously that this application runs completely within the browser. Additional benefits include the ability to use any fonts you wish and to create a PDF that can be sent to any publisher. The published version, as of August 2007, loads and edits only a single four-page brochure though it is built to load any size document. More ambitious versions were not only planned for but are also underway.
Take A Look: Brochure Builder