The following snippet:

    <Window x:Class="Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
        <Grid>
            <StackPanel Orientation="Horizontal"
                        VerticalAlignment="Center"
                        HorizontalAlignment="Center">            
                <Label Content="Name:"/>
                <Label Content="Itzhak Perlman" FontSize="44"/>
            </StackPanel>
        </Grid>
    </Window>

Produces the first label on top like in http://farm5.static.flickr.com/4034/4260633381_1a8a71c79b_o.png.

Is there any way to align the bottoms?
NOTE: I tried HorizontalAlignment, HorizontalContentAlignment, Margin, Padding.