In this article I have collated a few training links about .NET 4 and 4.5. I will keep adding to this page as I find other useful free resources. If you have any videos or articles that you feel would be useful here then please let me know in the comments and I will add them to the post. I would like it to be an archive of good material.
What’s New in .NET 4 and 4.5
New C# Features in the .NET Framework 4
What’s New in the .NET Framework 4.5
C# (C Sharp) 4.0 new Features- Optional Parameters,Named Parameters
C# (C Sharp) 4.0 new Features – Dynamic keyword/type
.NET 4/4.5 Asynchronous Programming
Asynchronous Programming with Async and Await
Asynchronous Programming using C# 4.5
Asynchronous Programming in .NET 4.5
.NET 4 Dynamic
C# 4.0 – Dynamic – Part 1 – Overview
C# 4 0 Dynamic Part 2 When to Use
C# 4.0 – Dynamic – Part 3 – Limitations
C# 4.0 – Dynamic – Part 4 – ExpandoObject
C# 4 0 Dynamic Part 5 DynamicObject
C# 4 0 Dynamic Part 6 StaticInvoker
Misc C#
Master Covariance and Contravariance in C# 4.0
C# 4.0 optional parameters example vs method overloading
Stephen Haunts { Freelance Trainer and Writer } 
C# 4.5 also introduces implicit casting of lambdas to delegates such that the new Action(()=>{}) syntax is unnecessary.
Also, both of us mean .Net 4.0 and 4.5, since C# has been up to version 5 since 2011.
Got any good links for it Hugh that you have found useful?