Microsoft has just released the first CTP preview of an "ASP.NET 3.5 Extensions" release that we've been working on. This release brings additional runtime functionality to ASP.NET and .NET 3.5. You can download it here (if you are using the MVC features also click here to download the MVC Toolkit extras).
This first ASP.NET 3.5 Extensions preview release includes:

• ASP.NET AJAX Improvements: New ASP.NET AJAX features in the ASP.NET 3.5 Extensions release include better browser history support (back/forward button integration, and server-side history management support), improved AJAX content linking support with permalinks, and additional JavaScript library improvements.

• ASP.NET MVC: This model view controller (MVC) framework for ASP.NET provides a structured model that enables a clear separation of concerns within web applications, and makes it easier to unit test your code and support a TDD workflow. It also helps provide more control over the URLs you publish in your applications, and more control over the HTML that is emitted from them.

• ASP.NET Dynamic Data Support: The ASP.NET 3.5 Extensions release delivers new features that enable faster creation of data driven web sites. It provides a rich scaffolding framework, and will enable rapid data driven site development using both ASP.NET WebForms and ASP.NET MVC.

• ASP.NET Silverlight Support: With the ASP.NET 3.5 Extensions release we'll deliver support for easily integrating Silverlight within your ASP.NET applications. Included will be new controls that make it easy to integrate Silverlight video/media and interactive content within your sites.

• ADO.NET Data Services: In parallel with the ASP.NET Extensions release we will also be releasing the ADO.NET Entity Framework. This provides a modeling framework that enables developers to define a conceptual model of a database schema that closely aligns to a real world view of the information. We will also be shipping a new set of data services (codename "Astoria") that make it easy to expose REST based API endpoints from within your ASP.NET applications.

We will be publishing many blog posts and videos discussing the new features in the weeks and months ahead. Click here to check out an initial set of Quickstart Samples that cover some of the new preview features.
Below you can find links to a few tutorial posts I've done (and a cool screencast by Scott Hanselman and some great testing tutorials by Phil Haack) that cover the new ASP.NET MVC Framework option. I'll be doing more posts on the non-MVC features in the extensions release in the weeks ahead as well:

• ASP.NET MVC Framework (Part 0): What is it?
• ASP.NET MVC Framework (Part 1): Building an MVC Application
• ASP.NET MVC Framework (Part 2): URL Routing
• ASP.NET MVC Framework (Part 3): Passing ViewData from Controllers to Views
• ASP.NET MVC Framework (Part 4): Handling Form Edit and Post Scenarios
• Scott Hanselman's ASP.NET MVC First Look Screencast
• TDD and Dependency Injection with the ASP.NET MVC Framework
• Writing Unit Tests for Controller Actions

To ask questions or get help, please visit these forums on http://forums.asp.net

• General ASP.NET 3.5 Extensions Preview Forum
• ASP.NET AJAX UI Forum
• ASP.NET MVC Framework Forum
• ASP.NET Dynamic Data Forum
• ADO.NET Data Services Forum