There are a couple of ways to go about it. If you're using MVC 2, you could use a DisplayTemplate. Just put a DateTime.ascx file in the folder called /Views/Shared/DisplayTemplates and the line of code it would have in it is:
<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl<System.DateTime?>" %>
<%: Model.HasValue ? Model.Value.ToShortDateString() : string.Empty %>
(Note: if you use the <%: syntax then you don't need the Html.Encode() because <%: does the HTML encoding for you - but that's only if you're using VS2010. If you're using MVC 2 with VS2008, then stick with the Html.Encode() for this part) Then in your view you would simply do this:
<%: Html.DisplayFor(m => m.BirthDate) %>
That will change the format to only have the Date for all DateTime's in your application. Of course you could put that directly in the view as well. But the DisplayTemplate will change it for all other DateTime's as well and you won't have to concern yourself with it in the view since it happens for your automatically.