Since VS 2010 is out with many new features and there aren’t many books out yet to cover them I am trying to collect resources where those goodies can be learned. Here is my compilation for ASP.NET 4 new features:

Core Services
Web.config File Refactoring
Extensible Output Caching
Auto-Start Web Applications
Permanently Redirecting a Page
Shrinking Session State
Expanding the Range of Allowable URLs
Extensible Request Validation
Object Caching and Object Caching Extensibility
Extensible HTML, URL, and HTTP Header Encoding
Performance Monitoring for Individual Applications in a Single Worker Process
Multi-Targeting

Ajax
jQuery Included with Web Forms and MVC
Content Delivery Network Support
ScriptManager Explicit Scripts

Web Forms
Setting Meta Tags with the Page.MetaKeywords and Page.MetaDescription Properties
Enabling View State for Individual Controls
Changes to Browser Capabilities
Routing in ASP.NET 4
Setting Client IDs
Persisting Row Selection in Data Controls
ASP.NET Chart Control
Filtering Data with the QueryExtender Control
Html Encoded Code Expressions
Project Template Changes
CSS Improvements
Hiding div Elements Around Hidden Fields
Rendering an Outer Table for Templated Controls
ListView Control Enhancements
CheckBoxList and RadioButtonList Control Enhancements
Menu Control Improvements
Wizard and CreateUserWizard Controls 56

ASP.NET MVC
Areas Support
Data-Annotation Attribute Validation Support
Templated Helpers

Dynamic Data
Enabling Dynamic Data for Existing Projects
Declarative DynamicDataManager Control Syntax
Entity Templates
New Field Templates for URLs and E-mail Addresses
Creating Links with the DynamicHyperLink Control
Support for Inheritance in the Data Model
Support for Many-to-Many Relationships (Entity Framework Only)
New Attributes to Control Display and Support Enumerations
Enhanced Support for Filters

Visual Studio 2010 Web Development Improvements
Improved CSS Compatibility
HTML and JavaScript Snippets
JavaScript IntelliSense Enhancements

Web Application Deployment with Visual Studio 2010
Web Packaging
Web.config Transformation
Database Deployment
One-Click Publish for Web Applications

Download PDF version of this whitepaper [1.13 MB]
What's New in ASP.NET 4 and Visual Web Developer on MSDN