On a Virtual Earth team blog they compare the three main MS mapping development platforms --
MapPoint 2006: Great for Thematic mapping, shaded area maps, disconnected/offline applications, Sharepoint Integration
MapPoint Web Service: Great for development on any operating system, server to server applications, stored procedures in databases with WS support, non-web client interfaces like WAP, mobile, voice, SMS, etc..., SharePoint Integration
Virtual Earth: Great for mashups, 3D web mapping, Web applications that need to present interactive maps and imagery.
Read more at -- Live Maps / Virtual Earth: If your only tool is a hammer...
What do you think?