var records:Array = new Array();
records.push({name:"john", city:"omaha", zip:68144});
records.push({name:"john", city:"kansas city", zip:72345});
records.push({name:"bob", city:"omaha", zip:94010});

for(var i:uint = 0; i < records.length; i++) {
trace(records[i].name + ", " + records[i].city);
}
// Results:
// john, omaha
// john, kansas city
// bob, omaha

trace("records.sortOn('name', 'city');");
records.sortOn(["name", "city"]);
for(var i:uint = 0; i < records.length; i++) {
trace(records[i].name + ", " + records[i].city);
}
// Results:
// bob, omaha
// john, kansas city
// john, omaha

trace("records.sortOn('city', 'name');");
records.sortOn(["city", "name"]);
for(var i:uint = 0; i < records.length; i++) {
trace(records[i].name + ", " + records[i].city);
}
// Results:
// john, kansas city
// bob, omaha

// john, omaha


Source: http://livedocs.adobe.com/flash/9.0/ActionScriptLangRefV3/Array.html#sortOn()