metaobject has released a new app for Mac users, BookLightning 1.0. BookLightning is a utility designed for PDF based booklet printing. The app features support for small books or magazines and prints two pages with a fold in the middle. According to metaobjects:
metaobject releases BookLightning, a lightweight imposition program for booklets and simple magazines
With BookLightning, you can create booklets for stapling or folding from any PDF file, or even directly from the Mac OS X print panel. It arranges the pages of a PDF files on sheets of paper in such a fashion that they will appear in the correct order when the resulting sheets are folded in the middle.
BookLightning is a fully native Cocoa application and requires a duplex printer for direct print support.
You can find more information about the BookLightning release at the metaobjects Web site. BookLightning is available for US$49.00.