@Chris
I am also having troubles displaying basemap layers (tilecache) in the WPF mobile app.
I have created both a raster mxd, made a tile schema with some scales and then generated the tiles. But the the mobile app is unable to show the raster image on the map.
I have also tried a vector mxd where I created a tile schema with some scales and generated some tiles. But in the Mobile Project Center, when I try to add the basemap layers, MPC sometime crashes. Sometime the basemap layers are added to MPC but when I load the project in ArcGIS Mobile, I don't see anything it is just a blank screen.
Do you mind posting in as much detail possible how you are able to load your basemaps from mxd creation to deploying the cache to the mobile device?
Thanks,
Akhil P.