Color Coding a map

[KeysleSorm]

Is it possible to color code this map?
I'd like to be able to color code the entire united states down to the individual cities.
As well as the cities in other parts of the world
Is this possible with this tool?

[dotMorten_esri]

You define how you want to render the map using ArcMap when you author your map. So when you publish this to the Server, Silverlight will automatically pull the map as you defined the rendering.
Other than that, you can do some changes to colors on the client if you use the FeatureLayer. See these examples:
http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#RenderersXAML
http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#Thematic_Interactive