A few days ago, ASP.NET MVC Preview 5 has been released that can be downloaded from http://www.codeplex.com/aspnet. In this release has two new stuffs: (a) Added global registration of view engine; (b) Changed the IVieew engine interface to add the RenderPartial method. Other improvements are: Added support for rendering partial view, added a parameter to specify a default option label for DropDownList control, Moved ASP.NET AJAX extension methods to a separate namespace, Added helpers for RadioButton and TextArea controls and made overall improvement to other helpers, and Remove helper method overloads to avoid ambiguity.
This new release has been used Routing Engine (System.Web.Routing) that shipped with Microsoft .NET Framework SP1. Make sure uninstall previous first before upgrade this release from previous release. This release is not compatible with Microsoft Visual Studio 2008 SP1 beta thus uninstall it first and install new RTM version of SP1. For more information about upgrading and installation, please read release notes that can be downloaded separately from installer package.