//Some date string you got from somewhere
var dateStr:String = "Sun Sep 25 22:30:33 GMT+0600 2011";
var date:Date = new Date(dateStr);
//Use date.toLocaleString() to get a local time string and create a new date from it
var localDate:Date = new Date(date.toLocaleString());
trace(localDate);'
Вот ссылка на date.toLocaleString () из Adobe
date.toLocaleString () Документация