Kirk Evans is a Microsoft Architect for the Azure Center of Excellence.
Introduction to SharePoint and Azure IaaS
Building SharePoint Apps with Windows Azure Platform as a Service
SharePoint Solutions and Architectures on Windows Azure Infrastructure Services
Understanding Authentication and Permissions with Apps for SharePoint and Office
G. Andrew Duthie shows how to use the ASP.NET 2.0 Active Directory Membership Provider . Sweet!
There is also coverage of this provider in the authentication section of the PAG guidance on security.