One of the major changes in AS3 is how you deal with XML content. While a lot of similarities carried over from the AS2 days, there are new time-saving niceties in AS3 that make working with XML files easier. One of the introductions is Ecmascript for XML, known as E4X for short. In this tutorial, you will gradually learn more XML tricks as you try to parse the various parts of the following XML data:
http://www.republicofcode.com/tutorials/flash/as3xml/
http://www.kirupa.com/developer/flashcs3/using_xml_as3_pg1.htm