On Katrien’s MSDN Blog:

During TechDays Belgium 2012 two weeks ago, Scott Guthrie announced the Beta release of ASP.NE MVC 4 slated for that same week. Since February 16th you can now download ASP.NET MVC4 Beta.
Interesting to note is the availability of a Go-Live license with this release. In other words, if you feel like using these bits on production you now can!

A few important updates and features are part of the Beta:

• - Bundling and Minification, brought to ASP.NET 4.5 and now also integrated into ASP.NET MVC 4. This allows you to build faster applications by minimizing the number of requests to the server (bundling requests).
  
• - Web API integration into ASP.NET: new support for creating HTTP REST services, has built-in support for content negotiation with support for JSON, XML and Form URL-encoded formats
  
• - ASP.NET Mobile support through custom view engines for mobile sit.es and jQuery Mobile integration.
  
• - Async and WebSockets: when using ASP.NET MVC 4 with .NET 4.5 and VS 11 you’ll also be able to take advantage of the new async and WebSocket support built-into .NET 4.5.
  
• - Single Page Applications: new in the beta is support for building better end-to-end experience for building applications with client-side interactions using JavaScript (Upshot, History.js) and the MVVM pattern (knockout.js). On the server side the ASP.NET NET Web API is used, mainly an abstract class DataController. Note this is a new project template type in experimental phase.
  
• For more information on creating Single Page Applications with ASP.NET MVC 4 I recommend you watch the fantastic session Steve Sanderson did during TechDays: Building rich Single Page Applications (SPAs) for desktop, mobile, and tablet with ASP.NET MVC 4. Worth watching until the end where Steve even shows an offline capable implementation using HTML5 application cache and offline storage. These latter ones however are not yet part of the beta.

Resources

• Download ASP.NET MVC 4
• Watch Scott Guthrie’s session going through ASP.NET MVC 4
• Watch Steven Sanderson’s session on Single Page Applications
• Read Scott Guthrie’s series on ASP.NET Web API
• Learning: new Intro to ASP.NET MV4 tutorial
• Learning: ASP.NET Web API Samples

Something I found that might come in handy:

The Microsoft All-In-One Code Framework is a free, centralized code sample library driven by developers' needs. Our goal is to provide typical code samples for all Microsoft development technologies, and reduce developers' efforts in solving typical programming tasks.

Codeplex page

Download (from Codeplex)

Request a code sample

For a full list of downloads (sorted by technology), please check the Codeplex download page. There are samples available for C++, ASP.NET, Silverlight, Azure, Office, Windows, WPF, Windows Security, and many more…

ScottGu introduced Microsoft's WebMatrix which is a small IDE to make web sites (ASP.NET and PHP). It actually includes everything you need: IIS Developer Express (a development Web server), ASP.NET (a Web framework), and SQL Server Compact (an embedded database). This product is aimed at developers and students who want an easy way to develop web sites. It is emphasized that all the knowledge and skill you gain using Microsoft WebMatrix is applicable to Visual Studio. WebMatrix is a 15MB download (50MB if you don’t have .NET 4 installed) and is quick to install.

Microsoft WebMatrix page
Microsoft WebMatrix Learning page
Scott Guthrie's WebMatrix post
Scott Hanselman's WebMatrix how-to

Resources (Getting started, tutorials (beginner and advanced), advanced learning

What’s new in ASP.NET MVC 2 

ASP.NET MVC on MSDN

ASP.NET MVC Forums

And last but not least: Download ASP.NET MVC 2