I have read it before, and most the site too, plus i own the book.
There is similar information in the airbus 319/20/21 documentation too, but there winglets are a little different, and i have never read which one works better if any?
There are some great testing videos from boeing on the research, they fitted winglets to B727 and B707and flew it through some sort of smoke rig.
I am sure i have seen some other footage too of normal wings going through the same rig, and that was a Mil Boeing, KC-135 i think.
When i was young i noticed a B727 with winglets and thought it was some sort of coolness statement, years later i realized what they was really there for.
Here is another link that i have read too, more reading...
http://www.aviationpartnersboeing.com/news/pdf/news/AT69winglets.pdf
http://www.enviro.aero/blog/2008/09/the-wind-beneath-our-winglets.html