Thank you Dominique, simply setting DisableClientCaching = true and Refresh() works. Since the user can move more than one point at a time and the the WCF service runs asynch I added a little logic to reset client caching after all points have been updated as shown below in case it helps any one else.TGIn my DrawComplete event handler
//turn off browser caching so updates show w/out needing to move the map
(_QueryLayer as ArcGISDynamicMapServiceLayer).DisableClientCaching = true;
UpdateCount = graphics.Count();
UpdateCount_Completed = 0;
foreach (Graphic g in graphics)
{
client.UpdateLocationAsync((int)g.Attributes["ID"], pt );
}
Then in the UpdateLocationAsync handler
(_QueryLayer as ArcGISDynamicMapServiceLayer).Refresh();
UpdateCount_Completed++;
if (UpdateCount_Completed == UpdateCount)
{
(_QueryLayer as ArcGISDynamicMapServiceLayer).DisableClientCaching = false;
}