Havinving been asked about building an application using Mappoint web service, I started searching the web. Here's a sample that I got from a google search.
There's this website, which offers a free trial. NACGeo
Mapquest has a free service for maps and driving directions at Mapquest API
It is not an XML Web Service, but it could be a possible solution.
Yahoo! Maps can also be used as described on Yahoo! Maps
3 months ago