Preview in Mac OS X 10.5 (Leopard) allows for PDF page rearrangement.
Let's say you have a 4-page PDF. What you want is to have pages 1,4 be on the "front" of the sheet and pages 2,3 to be on the back of the sheet. To do this:
1. Open the PDF in Preview.app.
2. Switch the Sidebar to Thumbnail view.
3. Simply drag Page 4 to be second in line (effectively making it Page 2)
4. Customize your print option (under Layout, choose Pagers Per Sheet: 2).
This becomes easier if your printer supports double-sided printing, otherwise you'd have to feed the sheet back in again yourself.
You can use other PDF editing software, such as
PDFPen, as well.