UPDATE (10/09/2009): A big thanks to Eric Weijers who pointed out in the comments below that the “Get Finder Items” action that I implemented in this workflow actually doubles up the pages that are in the resulting PDF. If you follow the instructions outlined in the post below, please make sure you don’t add the “Get Finder Items” action.
Before upgrading to Snow Leopard, I had made a few Automator actions that were saved as Finder plugins, and hence were accessible from Finder’s contextual popup window. However, after upgrading to Snow Leopard I found that these Finder plugins were gone (amongst other undesireable, but tolerable and fixable changes). After hearing about Services through the Apple Snow Leopard features page, and podcasts such as MacBreak Weekly, I decided to retool the Automator action as a Service instead.