javascript中怎么获取当前日期

javascript中如何获取当前日期?
我要计算距离奥运还有多少天,用javascript怎么弄?

------解决方案--------------------------------------------------------
<script type="text/javascript" language="javascript">
function DateDiff(interval,date1,date2){
 var long = date2.getTime() - date1.getTime(); //相差毫秒
 switch(interval.toLowerCase()){
case "y": return parseInt(date2.getFullYear() - date1.getFullYear());
case "m": return parseInt((date2.getFullYear() - date1.getFullYear())*12 + (date2.getMonth()-date1.getMonth()));
case "d": return parseInt(long/1000/60/60/24);
case "w": return parseInt(long/1000/60/60/24/7);
case "h": return parseInt(long/1000/60/60);
case "n": return parseInt(long/1000/60);
case "s": return parseInt(long/1000);
case "l": return parseInt(long);
 }
}
alert(DateDiff("d",new Date(),new Date(2008,8,8)));
</script>