The .NET Framework 4.5 beta includes several key new features and improvements.
.NET for Metro style Apps
Portable Class Libraries
Core New Features and Improvements
Windows Presentation Foundation (WPF)
Windows Communication Foundation (WCF)
Windows Workflow Foundation (WF)
If you want to run your apps that require .NET Framework 4.5 on Windows Azure, here is good news. Magnus Mårtensson, a Microsoft MVP, has put together a post that details the steps on how to install the framework and ASP.NET MVC 4 beta on Windows Azure. Check it out here.