Excel enables you to import your own custom XML Schema or public XML standards such as RosettaNet and bind the elements to a particular cell. Excel 2007 take one step further with the ability to detect detail line items and apply table formating as well as filtering when you drop the detail line onto the spreadsheet as below.

However there is a rule apply here, you must define the minOccurs and maxOccurs attribute in the element level (example here would be LineItem)

if you left out the minOccurs and maxOccurs attribute, Excel will not able to determine the element is a detail line.