The CLR team shows how to get more information from an error using Marshal.GetLastWin32Error.
Eric Lippert explains what “raising”,”hoisting” and “lifting” and currying means. In the next version of C# (version 5 I guess), we might even have observable collections, where they push data as events do. He has a great code puzzle about static and instance methods and how name collision resolution works in different scenarios.
Visual Studio 2010
If you do not want to change the security for your older projects, the CLR team shows how to enable CAS compatibility mode for a project.
Kirill Osenkov shows how much fun you can have in the new Visual Studio 2010 editor.
Rick Strahl explains how to use (local) transactions with LINQ to SQL.
John Teague has an interesting tip showing how adding a specific id to <body> allows you to have specific CSS for different code.
Billy McAfferty has an excellent post about the lessons he learned in practice.
Ian Cooper has a great article showing why choosing agile will allow your project to fail in a better way.