David Travis' article: '7 myths about paper prototyping' is basically making the point that it shouldn't be overlooked just because you aren't a confident sketcher or because you have a load of Visio templates. He makes a good case and it's well worth a read.
Paper has some distinct advantages over any other approach. Lots of drawbacks too, but it's all about recognising when it's the best approach.
I like Todd Warfel's definition of a prototype:
“…a conceptual model that captures the intent or idea of a design.”And that at the end of the day is the case David is making - if you can communicate the intent or idea of a design then it's a potentially suitable approach and shouldn't be dismissed.
7 myths about paper prototyping - article by David Travis for userfocus.com
Introduction to paper prototyping by Shawn Medero for A List Apart
Paper prototyping helper kit - Userfocus' PDF resources to print and cut out to assemble paper-based interfaces
10 Effective Video Examples of Paper Prototyping - a series of YouTube videos pulled together by Paul Andrew for speckyboy.com