The top 8 features and sub-features of the .NET Framework 4.0 and are listed below: 

Web Development

JavaScript Intellisense is supported in the Visual Studio Editor

One Click Deployment For Applications

RIA Support by providing Full fledged support for Silverlight

Cloud Development

Programmers can develop, debug, build, deploy services and applications for MS Cloud Platform

More Databases

Support for multiple vendor databases for various database developers.

Support for Developers

Context Sensitive Help System making Visual Studio 2010 more easy to write new code more efficiently.

VSTO

Support for Office 2010 Application Development making customized Office Application Development Easier.

Dynamic Support

Visual C# 2010 provides support for late binding to dynamic types by introducing a new type.

Better User Experience

Clear UI Organization

Reduced clutter and complexity

Improved editor

Better support for floating documents and windows

Enhanced document targeting

Focused animations for action feedback

Parallel Programming

Parallel programming is simplified, so both native- and managed-code developers can productively build innovative applications.

Visual Studio 2010 IDE support for parallel programming