For the last several preview releases, ASP.NET MVC features
have been split across two assemblies - System.Web.Mvc.dll and
Microsoft.Web.Mvc.dll. The later assembly + namespace contains
"futures" features that hadn't yet been committed to ship in the core
V1 product. As features become "committed" we move them from
the futures assembly into the core assembly - and also change the namespace
(from Microsoft.Web.Mvc to System.Web.Mvc).
The previous preview releases automatically shipped and
added the "futures" assembly when you did a File->New ASP.NET MVC
project. Starting with today's beta we are no longer automatically adding
this assembly - instead you need to explicitly add it from your project if you
want to use it. The reason for this is so that developers can clearly
distinguish those features that will be in the fully supported V1 product
(which implies product support and a higher commitment around backwards
compatibility), and those that might still evolve in the future (and not be
added to the supported product until vnext).
Important: the futures assembly (along with all the source
code in it) will continue to ship and will work with ASP.NET MVC V1. So
if there is a feature in it you really like, you do not have to worry about it
disappearing on you (it is still there and you can still use it). You
just now need to explicitly reference the assembly and use it in your
We plan to ship a version of the ASP.NET MVC Futures
assembly that works with the Beta later today. You will be able to
download it here.