Sun has a practical approach for identity management, as described in a recent white paper (in PDF) on sun.com, Keeping It Simple: A Pragmatic Approach to Identity Management. The paper first defines the importance of identity in Web applications and summarizes the subsequent chapters. Four chapters then follow, which focus on—

• The requirements for an effective identity infrastructure
• The pragmatic approach taken by Sun
• Sun's identity solutions
• Real-life examples

Reading a high-level writeup like that gives one a wide perspective. I enjoyed it.