well MSN acquired GeoTango on Christmas eve. GeoTango was owned by my GIS prof , Vincent Tao - a brilliant prof and entrepreneur. GeoTango had many patent algo like :
SilverEye, allows the rapid creation of 3D urban models from a single image.
Smart Digitizer is essentially a stand-alone tool for building GIS features: roads, rivers, hydrants, etc.
GlobeView has the ability to access data from a number of sources including servers supporting the Web Map Service Specification (WMS) from the Open Geospatial Consortium and Microsoft's own TerraServer.
So there is some competition with Google Earth in future.
As for my Prof, he is on leave (sabbastical) & having good vacation somewhere out there.