The Cadalyst web site is taking a quick poll on how people share their design data. Please visit http://www.cadalyst.com/cadalyst/ and look in the lower left of the site for an image that looks like:
Naturally we hope you vote for DWF; however, we know PDF is already installed on many machines. We are not delusional at Autodesk. PDF is popular. DWF is less popular but is specifically meant for design data. There are more Microsoft Word users than AutoCAD users. Would you really want to design your next project using Microsoft Word instead of AutoCAD (or Revit or Inventor)? So please only vote for DWF if you really use DWF. False statistics that inflate DWF usage do no one any good.