This mapping sample shows how to create repeating nodes from flat data inside the mapper. This sample also shows the use of some custom XSLT code inside the BizTalk mapper.
This sample works with BizTalk 2004 and BizTalk 2006.
Get more information from the original blog post on this topic: http://www.biztalkgurus.com/blogs/biztalk/archive/2004/10/28/How-To-Create-Nodes-from-Flat-Data-in-BizTalk-Maps.aspx