It is possible to generate a mapping file from a table of the database thanks to CodeSmith. I would be nice to have the possibility to do the same from the business layer as explained in this post :
http://community.codesmithtools.com/forums/t/7453.aspx
I think it would be nice to have a Visual Studio plugin that allow to graphically bind the properties of a class to the fields of a table. Under that, a mapping file would be generated. That could save much time even if we have to do some modification in the xml after that... Let me know if such a tool exists. ;-)