The steps that used to work for getting access to the IDesignerHost for a web
form no longer seem to work in Visual Studio 2005 Beta 1.  Below is the code
that works on 2003.  When running this code in 2005 the cast to IDesignerHost
always returns null.

   DTE dte = (DTE)GetService(typeof(DTE));
   HTMLWindow hw = dte.ActiveWindow.Object as HTMLWindow;
   object o = hw.CurrentTabObject;
   IOleServiceProvider oleSP = o as IOleServiceProvider;

   IntPtr pObject;
   Guid sid = typeof(IVSMDDesigner).GUID;
   Guid iid = typeof(IVSMDDesigner).GUID;
   int hr = oleSP.QueryService(ref sid, ref iid, out pObject);

   IDesignerHost designerHost = null;
   if (pObject != IntPtr.Zero)
   {
       try
       {
           System.Object obj = Marshal.GetObjectForIUnknown(pObject);
           designerHost = obj as IDesignerHost;
       }
       finally
       {
           Marshal.Release(pObject);
       }
   }