Could not load file or assembly 'System.Web.Abstractions, Version=3.5.0.0, Culture=neutral,

To resolve this problem

1. Download and Install .NET Framework 3.5 SP1 at
http://www.microsoft.com/downloads/thankyou.aspx?familyId=ab99342f-5d1a-413d-8319-81da479ab0d7&displayLang=en

2. Download and install ASP.NET MVC Release Candidate 2
http://www.microsoft.com/downloads/details.aspx?FamilyID=ee4b2e97-8a72-449a-82d2-2f720d421031&displaylang=en#filelist

3. Check that the 3 dlls are in the bin folder. Your application should work ;)
System.Web.Abstractions
System.Web.Routing
System.Web.Mvc