[Deff]

<style type="text/css">
#announcement {
  display:none;
  padding:1em;
  margin:0 auto;
  border:1px solid;
}
#announcement h2{
  border:1px #D8D3D3 solid;
  padding:3px 1em ;
  margin-bottom:0.7em;
  font-size:14px;
  font-weight:700;
  background-color:#F7F7F7;
}
#announcement .container{
  padding:1em;
  background:#F7F7F7;
  border:1px #D8D3D3 solid;
}
#date {
  font-size:12px;
  background:#E8F0FF;
  border:1px #D8D3D3 solid;
  font-weight:700;
  color:#467298;
  padding:1px 2px 2px;
  font-style: italic;
}
</style>
<div id="announcement" class="section">
<h2>Объявление:</h2>
   <div class="container">
    <!--Tут Ваш контент -->
 bla bla bla  bla bla bla  bla bla bla  bla bla bla  <br />
bla bla bla  bla bla bla  bla bla bla  bla bla bla  bla bla bla  <span id=date></span>
   </div>
</div>

<script type="text/javascript">
var This_Date = new Date(); //Sun Aug 05 2012 16:35:53 GMT+0400
day = This_Date.getDay();

th_DAT = This_Date.toString().replace(/(\S+?) (\S+?) (\S+?) (\S+?) (\d\d:\d\d).*$/ig,' Воскресенье: $3 - $2 - $4 $5');
hour = This_Date.getHours();

if(day==0&&hour<20){//alert(th_DAT)
   var b=document.getElementById("announcement");
   b.document.getElementById("date").innerHTML = th_DAT;
   b.style.display='block';
}
</script>