Some links by Gena
http://www.opengeospatial.org/standards/as - The OpenGIS® Abstract Specification Topic 6: Schema for coverage geometry and functions
Network Analyst (there are videos in Demo showing how it works)
http://www.esri.com/software/arcgis/extensions/networkanalyst/about/features.html
http://google-latlong.blogspot.com/2007/06/its-click-drag-situation.html - Google routes
http://maps.google.com/help/maps/directions/
- can be interesting for Urban version, streets