If you want Razor (why would you not ;-) you could try this:

@{
    umbraco.MacroEngines.DynamicNodeList list = Model.AncestorOrSelf().DescendantsOrSelf();
    var newest = list.Items.OrderByDescending(x => x.UpdateDate).Take(3);
    foreach(dynamic item in newest){
        <ul>
            <li>@item.Name li>
        <ul>
    }
}

In this case you lose the 'dynamic' of the DynamicNode though, because of the cast to DynamicNodeList.

There is some bug in the DynamicNode OrderBy which makes it impossible to use:

var newest = @Model.AncestorOrSelf().DescendantsOrSelf().OrderBy("updateDate desc").Take(3);

This gives you just the first 3 items , not ordered by updateDate at all.

Cheers!

Richard