Interested in learning about claim-based identity and how you can leverage it to implement access control in your applications? The Patterns & Practices group in Microsoft has recently released "A guide to Claims-Based Identity and Access Control", a guide that, without getting too deep in the technicalities and standards involved by claim-based identity, is a nice introduction to this very hot topic. Get your PDF copy of this guide here. Along with this guide the P&P group has also provided source code samples (SingleSignOn, Federation, FederationWithMultiplePartners, ActiveClientFederation and WindowsAzure) to play with. Finally, on CodePlex you will find a community site that you might care to check out.