I waited so long on regards this issue to be coming out with much more stable version, and I am not a great beleiver of beta versions but I think MVC Beta framework is kind of stable one and ready to use (I admit it my - fingers are burning in order to start working with this great tool), one more thing is that the Beta release comes with an explicit "go-live" license that allows you to deploy it in production environments.
The ASP.NET MVC Beta works with both .NET 3.5 and .NET 3.5 SP1, and supports both VS 2008 and Visual Web Developer 2008 Express SP1 (which is free - and now supports class libraries and web application project types).
You can download it from Scott Guthrie's blog here and read some more details on regards this issue.
Great examples and web casts you can find here.
My point of view on regards this issue is quite clear - I am supporting this methodology and work-scheme over the traditional asp.net webform that does simple round-trip to the server and back. One more thing is that traditional asp.net webforms were being done much more heavier and with low performance where including vast logic - not including asp.net AJAX controls (ScriptManager, UpdatePanel etc...) that make the page process to be much more slow and not intuitive;
MVC framework got me back to the traditional web development, while using simple HTML code that does simple submit to the server and shows the server-side data in fewer code while not using asp.net server controls at all.
One more great featutre that MVC supplies according to it behavior is explicit URLs patterns. This one helps to SEO against search engines - something that comes out of the box and you don't need to implement it like on regular asp.net webforms; that means MVC is perfect to content websites that suppost to be indexed by the search engines.
The main question is why Microsoft came out with this framework so lately, you know MVC methodology is exists for years...