I use ESRI tiled street map service WKID=102100 in our Silverlight application for City of Houston. the map needs to be zoom in further Houston area. But the tiled map only can zoom in certain scale. Does ESRI have anyway or plan to fix the problem?
Which service are you using? And what scale would you like to zoom in to?
May be one of the other ArcGIS Online services could work better for you. Using the one below I can zoom in to Houston and see building footprints for residential homes.