Things I Have Been Reading Lately

http://spg.codeplex.com/
A new drop of the official SharePoint Guidance. It now covers SharePoint 2010 and further expands on the SharePoint solution architectural decisions and implementation guidelines.

http://webclientguidance.codeplex.com/ 
After some time using Web Client Software Factory (WCSF) guidance from Microsoft p&p team, they are now coming with a new version of web client guidance, oriented to ASP.NET with jQuery, AJAX and even ASP.NET MVC. Excellent read, even in the present rough form.

http://msdn.microsoft.com/en-us/library/ff423674.aspx
http://claimsid.codeplex.com/  
A guide to Claims-based Identity and Access Control, with a downloadable book in PDF format. It’s invaluable in understanding the new Windows Identity Framework (former Geneva Framework) and SharePoint 2010 claims-based authentication.

http://msdn.microsoft.com/en-us/library/cc949034.aspx
http://www.codeplex.com/WCFSecurityGuide 
Web Service Security Guidance for WCF, available as an online book and as a PDF file. I admit that WCF is a huge step forward in distributed applications but the security implications are too important to be left unattended. After reading this guide I had clearer image of all those pesky web.config WCF tags and their effect. Priceless when you are debugging cross-domain WCF calls :-)