Microsoft has released ASP.NET MVC 2 RTM for Visual Studio 2008 SP1.

Note Because Visual Studio 2008 and Visual Studio 2010 RC share a component of ASP.NET MVC 2, installing the ASP.NET MVC 2 RTM release on a computer where Visual Studio 2010 RC is also installed is not supported.

New Features in ASP.NET MVC 2 RTM
The following features are new since the RC release of ASP.NET MVC 2.
Templated Helpers Allow You to Specify Extra View Data
ASP.NET MVC 2 now includes new overloads of the EditorFor and DisplayFor methods. These overloads contain a parameter that accepts an anonymous object that can be used to provide extra view data. The view data provided in this parameter is merged with any existing view data that is passed to the template.

ASP.NET MVC 2 RTM for Visual Studio 2008 SP1 can be downloaded from the following page: http://go.microsoft.com/fwlink/?LinkID=157074

Make sure to also download and read ASP.NET-MVC-2-RTM-Release-Notes.doc. This document has the release notes and the know issues.

To learn how to upgrade an ASP.NET MVC 1.0 application to ASP.NET MVC 2 in Visual Studio 2008 SP1 visit this link: http://www.asp.net/learn/whitepapers/aspnet-mvc2-upgrade-notes/