I\'m trying to use updatemodel(myItem, formcollection) with asp.net mvc 2 but it fails with the stack trace below.
at System.Web.Mvc.FormCollection.GetVal
This is a confirmed bug in MVC 2 RC. If you have the MVC source, you can remove the String.IsNullOrEmpty() check from FormCollection.GetValue(), recompile, and redeploy. The FormCollection class is at src\SystemWebMvc\Mvc\FormCollection.cs. The team is aware of it and a fix is planned for the next preview.
Had the same issue here when trying to look at Orchard CMS. Lets hope they fix it soon.