Just finished reading an article on MSDN by my good friend Ingo: "Using Role-Based Security with Web Services Enhancements 2.0". Very nice, and it helped clear up for me how a few parts of the WSE security infrastructure fit together.
One minor nitpick: In the paragraph right after Figure 1, you say "As soon as you select this check box, a number of different things happen. First, a reference to Microsoft.Web.Services.dll will automatically be added to your project.". This should be Microsoft.Web.Services2.dll instead, since the article is about WSE 2 :)