<?xml version="1.0" encoding="utf-8" ?>
<Pages>
  <Page Name="Page1" Uri="/FrameContent;Component/Page1.xaml"/>
  <Page Name="Page2" Uri="/FrameContent;Component/Page2.xaml"/>
</Pages>

<ListBox x:Name="ListBox1"
          ItemsSource="{Binding Source={StaticResource ListSource}}" 
          DisplayMemberPath="@Name"/>
<!-- 最简单的方式就是用Frame的Source来做绑定，不过这样会导致每次都生成新的实例 -->
<Frame DataContext="{Binding ElementName=ListBox1, Path=SelectedItem}" 
       Source="{Binding XPath=@Uri}"/>

<ListBox x:Name="ListBox1"
         ItemsSource="{Binding Source={StaticResource ListSource}}" 
         DisplayMemberPath="@Name"/>
<Frame x:Name="PageHost1"
       NavigationUIVisibility="Hidden"
       Content="{Binding ElementName=ListBox1, Path=SelectedItem, Converter={StaticResource Converter}}"/>

public class FrameContentConverter : IValueConverter
    {
        // 使用Page池来减少创建Page的开销
        private Dictionary<string, Page> _pagePool = new Dictionary<string, Page>();

        IValueConverter Members#region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            // 把Frame的Content绑定到ListBox的SelectedItem上，无法对变化做出响应
            XmlElement node = value as XmlElement;
            if (node != null)
            {
                string name = node.Attributes["Name"].Value;
                string uri = node.Attributes["Uri"].Value;

                if (this._pagePool.ContainsKey(name))
                {
                    return this._pagePool[name];
                }
                else
                {
                    Page page = Application.LoadComponent(new Uri(uri, UriKind.Relative)) as Page;
                    this._pagePool.Add(name, page);
                    return page;
                }
            }
            return null;
        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
        {
            XmlElement node = value as XmlElement;
            if (node != null)
            {
                string name = node.Attributes["Name"].Value;
                string uri = node.Attributes["Uri"].Value;

                if (this._pagePool.ContainsKey(name))
                {
                    return this._pagePool[name];
                }
                else
                {
                    Page page = Application.LoadComponent(new Uri(uri, UriKind.Relative)) as Page;
                    this._pagePool.Add(name, page);
                    return page;
                }
            }
            return null;
        }

        #endregion
    }

<ListBox x:Name="ListBox2" 
         ItemsSource="{Binding Source={StaticResource ListSource}}"
         DisplayMemberPath="@Name"
         SelectedItem="{Binding ElementName=PageHost2, Path=Content, Converter={StaticResource Converter}, Mode=OneWayToSource}"/>
<Frame x:Name="PageHost2" NavigationUIVisibility="Hidden"/>