It looks like by using the ScrollableMap sample, I posted a few days ago (http://resources.esri.com/arcgisserver/apis/silverlight/index.cfm?fa=codeGalleryDetails&scriptID=169...), it should work inside a listbox (even without using the scrollviewer capabilities).Without scrollviewer for the item:<ListBox Margin="0,5,0,10">
<local:ScrollableMap>
<esri:Map x:Name="LocalMap" Width="600" Height="400" >
<esri:ArcGISTiledMapServiceLayer ID="MyLayer"
Url="http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer" />
</esri:Map>
<local:ScrollableMap>
</ListBox>
With a scrollviewer for panning the map:<ListBox Margin="0,5,0,10">
<ScrollViewer ScrollViewer.HorizontalScrollBarVisibility="Auto" ScrollViewer.VerticalScrollBarVisibility="Auto">
<local:ScrollableMap>
<esri:Map x:Name="LocalMap" Width="600" Height="400" >
<esri:ArcGISTiledMapServiceLayer ID="MyLayer"
Url="http://server.arcgisonline.com/ArcGIS/rest/services/ESRI_StreetMap_World_2D/MapServer" />
</esri:Map>
<local:ScrollableMap>
</ScrollViewer>
</ListBox>