ASP.NET MVC 1.0 Release Candidate has been made available for download, you can get the download here http://go.microsoft.com/fwlink/?LinkID=141184&clcid=0×409
You can grab the release notes here: http://go.microsoft.com/fwlink/?LinkID=137661&clcid=0×409
ASP.NET MVC 1.0 Release Candidate is the last public release of ASP.NET MVC that Microsoft will ship prior to the final ’1.0′ release. Microsoft expects to ship the final ASP.NET MVC 1.0 release next month.
Of course I can tell you all the things that are new and wonderful but Scott Guthrie will do a much better job, you can read his announcement here: http://weblogs.asp.net/scottgu/archive/2009/01/27/asp-net-mvc-1-0-release-candidate-now-available.aspx