Conclusion
The different authentication/authorization options shown in these two articles (and, specifically, the operation based security infrastructure we've just covered) should give you a head start for .NET Security. Although based on Windows identity in this article, the operation based authentication logic works without problems when used together with a custom authentication scheme as well.
The third and final article in this series will cover the issues related to identity impersonation and identity flow across a .NET distributed, multilayered application (the twos are actually strictly related). Stay tuned.