The very interesting consumer survey put out late last year from WebVisible and Nielsen is now available in a final report (with nice graphics and tables, etc.). You’ve seen the data and the various write-ups; now you can get a copy of the report by emailing David Reeve (dreeve (at) webvisible.com).
Screenwerk 
January 10, 2008 at 2:11 am
Did a Facebook poll on the topic a while back that showed that 29% of Facebook users do that (while 55% buy online): http://seoroi.com/latest-news/55-facebook-users-have-shopped-bought-online-this-past-year/