This is a quick sample thrown together that demonstrates some of the capabilities of the ArcGIS API for Microsoft Silverlight.
http://maps.esri.com/police/default.aspx

Video in Map Tooltips

One intriguing feature is the ability to extend ESRI’s map tips with multimedia content.  In the police sample, video hosted by the server is streamed into the map tip.

The following XAML shows how this is achieved.

<esri:Map>
    <esri:Map.Layers>
        <ve:TileLayer Opacity="0" LayerStyle="AerialWithLabels"/>
        <ve:TileLayer Opacity="1" LayerStyle="Road"/>
        <esri:GraphicsLayer>
            <esri:GraphicsLayer.MapTip>
                <StackPanel Orientation="Vertical" Background="Transparent">
                    <TextBlock Text="..."/>
                    <Border
                        Width="200"
                        Height="150"
                        BorderBrush="SkyBlue"
                        BorderThickness="1"
                        HorizontalAlignment="Right"
                        VerticalAlignment="Top"
                        >
                        <Border.Background>
                            <VideoBrush
                                SourceName="video"
                                Stretch="UniformToFill"
                                />
                        </Border.Background>
                    </Border>
                </StackPanel>
            </esri:GraphicsLayer.MapTip>
        </esri:GraphicsLayer>
    </esri:Map.Layers>
</esri:Map>

Where “video” is defined as:

<MediaElement 
    x:Name="video" 
    AutoPlay="True"
    Source="police-video-large.wmv"
    IsMuted="True"
    Opacity="0"
    IsHitTestVisible="False"
    MediaEnded="Video_MediaEnded"
    />

Animated Graphics

The Silverlight animation environment is very powerful.  This power can be leveraged by the ArcGIS API for Silverlight.  For example, the incident graphics are displayed as a red icons with a rotating swirl.  There are three animations in action here:

1. The graphic enlarges when the user’s mouse hovers over it,
2. The red swirl rotates clockwise, and
3. The red swirl gradually fades out over ten seconds.

This behavior can be achieved by subclassing the ESRI MarkerSymbol and overloading the common and mouseover view states.

IncidentSymbol.cs

using System.IO;
using System.Windows.Controls;
using System.Windows.Markup;
using ESRI.ArcGIS.Symbols;

namespace ESRI.PrototypeLab.PoliceDispatcher {
    public class IncidentSymbol : MarkerSymbol {
        public IncidentSymbol() : base() {
            string key = "<your namespace>.IncidentSymbol.xaml";
            Stream stream = typeof(IncidentSymbol).Assembly.GetManifestResourceStream(key);
            string template = new StreamReader(stream).ReadToEnd();
            this.ControlTemplate = XamlReader.Load(template) as ControlTemplate;
        }
    }
}

IncidentSymbol.xaml

<ControlTemplate
    xmlns="http://schemas.microsoft.com/client/2007"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:sys="clr-namespace:System;assembly=mscorlib"
    xmlns:vsm="clr-namespace:System.Windows;assembly=System.Windows"
    >
    <Grid
        Cursor="Hand"
        RenderTransformOrigin="0.5,0.5"
        Height="50"
        Width="50"        
        >
        <Grid.RenderTransform>
            <TransformGroup>
                <ScaleTransform x:Name="scale" ScaleX="1" ScaleY="1" />
                <TranslateTransform X="-25" Y="-25"/>
            </TransformGroup>
        </Grid.RenderTransform>
        <vsm:VisualStateManager.VisualStateGroups>
            <vsm:VisualStateGroup x:Name="CommonStates">
                <vsm:VisualState x:Name="Normal">
                    <Storyboard>
                        <DoubleAnimation 
                            Storyboard.TargetName="rotateTransform"
                            Storyboard.TargetProperty="Angle"
                            From="0" To="360"
                            Duration="0:0:3"
                            RepeatBehavior="Forever"
                            />
                    </Storyboard>
                </vsm:VisualState>
                <vsm:VisualState x:Name="MouseOver">
                    <Storyboard>
                        <ObjectAnimationUsingKeyFrames
                            Duration="0"
                            Storyboard.TargetName="path"
                            Storyboard.TargetProperty="Visibility"
                            >
                            <DiscreteObjectKeyFrame KeyTime="0" Value="Collapsed"/>
                        </ObjectAnimationUsingKeyFrames>
                        <DoubleAnimation
                            BeginTime="0:0:0"
                            Storyboard.TargetName="scale"
                            Storyboard.TargetProperty="ScaleX"
                            To="2"
                            Duration="0:0:0.2"
                            />
                        <DoubleAnimation
                            BeginTime="0:0:0"
                            Storyboard.TargetName="scale"
                            Storyboard.TargetProperty="ScaleY"
                            To="2"
                            Duration="0:0:0.2"
                            />
                    </Storyboard>
                </vsm:VisualState>
            </vsm:VisualStateGroup>
            <vsm:VisualStateGroup x:Name="SelectionStates">
                <vsm:VisualState x:Name="Selected" />
                <vsm:VisualState x:Name="Unselected" />
            </vsm:VisualStateGroup>
        </vsm:VisualStateManager.VisualStateGroups>
        <Image
            HorizontalAlignment="Center"
            VerticalAlignment="Center"
            Height="32"
            Width="32"
            Source="ESRI.PrototypeLab.PoliceDispatcher;component/Images/incident.png"
            />
        <Path x:Name="path" Opacity="1" >
            <Path.Data>
                <PathGeometry>
                    <PathGeometry.Figures>
                        <PathFigureCollection>
                            <PathFigure StartPoint="25,0" IsClosed="True">
                                <PathFigure.Segments>
                                    <PathSegmentCollection>
                                        <ArcSegment
                                            Point="50,25"
                                            Size="25,25"
                                            SweepDirection="Clockwise"
                                            IsLargeArc="False"
                                            RotationAngle="0"
                                            />
                                        <LineSegment Point="45,25"/>
                                        <ArcSegment
                                            Point="25,5"
                                            Size="20,20"
                                            SweepDirection="Counterclockwise"
                                            IsLargeArc="False"
                                            RotationAngle="0"
                                            />
                                    </PathSegmentCollection>
                                </PathFigure.Segments>
                            </PathFigure>
                        </PathFigureCollection>
                    </PathGeometry.Figures>
                </PathGeometry>
            </Path.Data>
            <Path.Fill>
                <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
                    <GradientStop x:Name="color1" Color="#00FF0000" Offset="0"/>
                    <GradientStop x:Name="color2" Color="#FFFF0000" Offset="1"/>
                </LinearGradientBrush>
            </Path.Fill>
            <Path.RenderTransform>
                <TransformGroup>
                    <RotateTransform x:Name="rotateTransform" Angle="0" CenterX="25" CenterY="25" />
                </TransformGroup>
            </Path.RenderTransform>
        </Path>
    </Grid>
</ControlTemplate>