I know this is minor, however I just ran into a collision between one of the default MVC LabelFor helpers and an Orchard helper. Basically, this method:
public static IHtmlString LabelFor<TModel, TValue>(this HtmlHelper<TModel> html, Expression<Func<TModel, TValue>> expression, string labelText)
conflicts with one of the default overloads in mvc. The simple workaround, and the way it probably should be used is to use the localized overload. The only reference to the non-localized method is in the same class, so I think it would be safe to mark it as private. I'm attaching a patch which does that.