Well, I kind off solved it.
Thanks deerchao for the web.config tip. I forgot to look at the views config file as well. The new project contained a little more data like this:
<pages
validateRequest="false"
pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
<controls>
<add assembly="System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />
</controls>
</pages>
As you can see, the pages item has now a couple more attributes linked to types. After copy/past this in my old project, the page got loaded.
But then I got the same problem as Nairb was mentioning. When trying to open the view in the IDE, it just shuts down.
I "solved" this by uninstalling the "Visual Studio 2008 PowerCommands" plug in.
So besides loosing this plug-in, the project runs again.
Few more notes...
A new created project with RC1 works perfect with the PowerCommands plug in
I still don't see the System.Web.Mvc reference in the "Add Reference" dialog altough it is installed in the GAC (gacutil)