I've been messing with ArcGIS Mobile and I get that it loads and caches layers from an ArcGIS Server for disconnected use. I'm wondering if it supports layers where data is loaded from a layer in realtime? I can't find any examples where I create a layer, give it a URL and have it load imagery data as I pan the map.
According to the documentation, the answer is yes you can use Google or Bing basemaps in ArcGIS for Windows Mobile. You can also use ArcGIS Online free of charge if you don't have your own ArcGIS Map Server.