Download Microsoft .NET Framework 4 RC
Microsoft .NET Framework 4 is now out of beta stage and its RC build is available for download. The redistributable package installs the .NET Framework runtime and associated files that are required to run and develop applications.
It works side by side with older Framework versions. Applications that are based on earlier versions of the Framework will continue to run on the version targeted by default.
You can check the new features and improvements on their site.
Download Here (32 & 64-bit version )