You can check out the new map docs. There any now a few ways to add push pins to the map. You can add MapIcons through code to the MapElements collection (I have yet to get a collection of MapIcons binding in xaml).
Map.MapElements.Add(new MapIcon());
You can bind a collection of places using the MapItemsControl. You can place any xaml in the ItemTemplate of the control.
<maps:MapControl x:Name="Map" MapServiceToken="abcdef-abcdefghijklmno">
<maps:MapItemsControl ItemsSource="{Binding Locations}">
<maps:MapItemsControl.ItemTemplate>
<DataTemplate>
<Image Source="Assets/Mappin.png" Height="25"
maps:MapControl.NormalizedAnchorPoint="1,0.5"
maps:MapControl.Location="{Binding Geopoint}" />
</DataTemplate>
</maps:MapItemsControl.ItemTemplate>
</maps:MapItemsControl>
</maps:MapControl>
Hope that helps.