Directions Media's e-news had an article today on routing that is likely to be of interest to folks on this list. The article gives a brief introduction on how routing works, types of routing (based on distance, time, and hierarchical routing), and a discussion of routing road network data (albeit, the bias is toward US TIGER data). The direct link to the article is: http://www.directionsmag.com/articles/introduction-to-road-data-part-1/130105
Dan