A new article on MSDN about the new security features in ASP.NET 2.0:
From the article - ASP.NET 2.0 builds on ASP.NET 1.x to enable you to more easily create and manage users, and to password-protect pages in a Web application. The new framework includes new features for working with authentication and authorization, which were designed to appeal to both Web site administrators and developers.
Web site administrators can take advantage of the new Web Site Administration Tool to create new users and roles, and to control access to pages in a Web application. The Web Site Administration Tool is a set of prewritten ASP.NET pages that can be used by individuals with no programming skills to configure a Web application.
Developers can take advantage of the new Login controls in order to quickly build security related pages in a Web application. For example, a developer can create a login page simply by dragging a Login control onto an .aspx page. By taking advantage of the Login controls, a developer can build a login page, a registration page, or a password recovery page without writing any code.
Finally, the ASP.NET 2.0 framework contains new security related features which will appeal to advanced developers. The new Membership API is a set of classes that contains methods for creating and retrieving information about application users. In addition, the new framework contains classes that make it easier to work with custom user roles.
Check out the article here.