Things in .NET Framework 4 that every programmer should know [closed]

Answer 1

Enum.TryParse

Guid.TryParse

Answer 2

Code contracts look very promising both from the standpoint of creating more correct code but also from the point of producing more complete documentation. Sadly they aren't all there in VS2010 yet - you have to install an add-on and even then it's neither complete nor finished and appears to still be a work in progress.

Answer 3

string.Join() now has a signature that takes IEnumerable<T> instead of just string[] - a small improvement that allows you to rip out your .Select() and .ToArray() code.

Answer 4

I just love the fact that web.config file is small and meaningful, instead of long and full of unknown statements...