There’s a cheap new app out called ‘Booklet’ which allows you to make a booklet from a pdf. (You can download it from the App Store for $1.49.) The icon won’t win any design awards but the app works OK. Here’s how to add it to your print dialog for easy access.
Go to the print dialog by selecting print from the file menu as if you are about to print a document.
Select ‘Edit Menu’
Press the ‘+’ button, go into Applications and select ‘Booklet’ (which you have previously downloaded from the App Store.)
There will now be an option in the ‘PDF’ menu called ‘Booklet’ which you can access from your print menu from whenever you want to print a booklet.