Installation link for MVC4:

http://www.microsoft.com/web/handlers/webpi.ashx?command=getinstallerredirect&appid=MVC4VS2010_Loc

New Features in ASP.NET MVC4:

a.       ASP.NET Web API

ASP.NET MVC 4 includes ASP.NET Web API, a new framework for creating HTTP services that can reach a broad range of clients including browsers and mobile devices. ASP.NET Web API is also an ideal platform for building RESTful services.

b.      Enhancements to Default Project Templates

The template that is used to create new ASP.NET MVC 4 projects has been updated to create a more modern-looking website.

c.       Mobile Project Templates

If you’re starting a new project and want to create a site specifically for mobile and tablet browsers, you can use the new Mobile Application project template. This is based on jQuery Mobile, an open-source library for building touch-optimized UI.

d.      Display Modes

The new Display Modes feature lets an application select views depending on the browser that's making the request. For example, if a desktop browser requests the Home page, the application might use the Views\Home\Index.cshtml template. If a mobile browser requests the Home page, the application might return the Views\Home\Index.mobile.cshtml template.

e.      jQuery Mobile, the View Switcher, and Browser Overriding

Mobile applications with ASP.NET MVC 4 using jQuery Mobile.

f.        Task Support for Asynchronous Controllers

You can now write asynchronous action methods as single methods that return an object of type Task or Task<ActionResult>.

g.       Azure SDK

ASP.NET MVC 4 supports the 1.6 and newer releases of the Windows Azure SDK.

h.      Database Migrations

ASP.NET MVC 4 projects now include Entity Framework 5. One of the great features in Entity Framework 5 is support for database migrations. This feature enables you to easily evolve your database schema using a code-focused migration while preserving the data in the database.

i.     Empty Project Template

The MVC Empty project template is now truly empty so that you can start from a completely clean slate. The earlier version of the Empty project template has been renamed to Basic.

j.    Add Control to any project folder

You can now right click and select Add Controller from any folder in your MVC project. This gives you more flexibility to organize your controllers however you want, including keeping your MVC and Web API controllers in separate folders.

k.       Bundling and Minification

The bundling and minification framework enables you to reduce the number of HTTP requests that a Web page needs to make by combining individual files into a single, bundled file for scripts and CSS. It can then reduce the overall size of those requests by minifying the contents of the bundle. Minifying can include activities like eliminating whitespace to shortening variable names to even collapsing CSS selectors based on their semantics. Bundles are declared and configured in code and are easily referenced in views via helper methods which can generate either a single link to the bundle or, when debugging, multiple links to the individual contents of the bundle.

l.     Enabling Logins from Facebook and Other Sites Using OAuth and

OpenID

The default templates in ASP.NET MVC 4 Internet Project template now includes support for OAuth and OpenID login using the DotNetOpenAuth library.