Check out the new definitions that have just been posted:

The Data Access Layer - http://www.psdn.com/library/entry.jspa?externalID=1461&categoryID=110

Data Source Object - http://www.psdn.com/library/entry.jspa?externalID=1460&categoryID=110

and last, but certainly not least

Model View Controller Pattern - http://www.psdn.com/library/entry.jspa?externalID=1462&categoryID=107

Happy Reading!