olá hutuh, obrigado pela força...mas não conheço quase nada de php...meu código tá assim: 
  
<?php
 
header('Content-Type: text/html; charset=utf-8', true); 
 
require("u_funcoes.php");
$xCon = pConecta();
 
$cod_key  = $_POST["cod_key"];
 
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script src="jquery-1.7.1.js" type="text/javascript"></script>
<script src="jquery.maskedinput-1.3.js" type="text/javascript"></script>
<script src="u_funcoes.js" type="text/javascript">
 
</script>
<script>
$(document).ready(function(){
   $('#sbotao').click(function(){
   horacerta = $('#sbotao').val();
   $('#colunaEsquerda').load('u_agendamento_exames.php',{sbotao:horacerta})
}
</script>
<style type="text/css"> 
<!-- 
body  {
margin: 0; 
padding: 0;
text-align: center;
color: #000000;
}
.twoColFixRt #principal { 
width: 780px;  
margin: 0 auto; 
border: 1px solid #000000;
text-align: left; 
}
.twoColFixRt #colunaDireita {
    float: right; width: 30%; 
    margin-right:: 50%; 
margin-top: inherit;
}
 
.twoColFixRt #colunaEsquerda { 
    float: left; width: 30%; 
    margin-left: inherit; 
margin-top:  inherit;
} 
.fltrt {
float: right;
margin-left: 8px;
}
.fltlft { 
float: left;
margin-right: 8px;
}
.clearfloat {
   clear:both;
    height:0;
    line-height: 0px;
}
 
--> 
</style><!--[if IE 5]>
<style type="text/css"> 
.twoColFixRt #sidebar1 { width: 220px; }
</style>
<![endif]--><!--[if IE]>
<style type="text/css"> 
.twoColFixRt #sidebar1 { padding-top: 30px; }
.twoColFixRt #mainContent { zoom: 1; }
</style>
<![endif]--></head>
 
<body class="twoColFixRt">
<div id="principal" >
  <div id="colunaEsquerda"  align="left">
    
    <?   
session_start();
    $DataExame2 = $_GET["dataini"];
    echo $DataExame2;             
 
    $_SESSION['DataExame'] = $_GET["dataini"]; 
?>
    <h1 > Manhã </h1>
    
    <form action="u_encaminhamento_exames.php?cod_key=1" method="post" enctype="application/x-www-form-urlencoded" name="fEnc" id="fEnc">
       <?php           
 
      //cria sessão
     
      $hora     = '06:55';
      
      date_default_timezone_set('Brazil/East'); 
      $ibotao = 0; 
     for ($i = 0; $i < 60; $i++) 
 
 {    ?>
        <div>
           <tr>
              <td>
         <?php  
            $horaNova = strtotime("$hora + 5 minutes");
   $horaNovaFormatada = date("H:i",$horaNova);
                $hora = $horaNovaFormatada; 
   if ($hora == '12:00'){
            $hora = '12:55';
            $horaNova = strtotime("$hora + 5 minutes");
           $horaNovaFormatada = date("H:i",$horaNova);
                   $hora = $horaNovaFormatada; 
   } 
 
      $ibotao++;
 
             $sdt = substr($DataExame2,6,4)."-".substr($DataExame2,3,2)."-".substr($DataExame2,0,2); 
$xSql = "select distinct a.data_cad, a.cod_id, a.cod_idfun, a.hora, a.nome_fun
       from mv_exames_agenda a where (a.data_cad = '".$sdt."' ) and( a.hora = '".$hora."' )";
 
                $xRes = $xCon->Execute($xSql);
              
                if ($xRes->RecordCount() > 0) { ?>
                    <input type="submit" value=<?php print("$horaNovaFormatada");?>  name="sbotao" disabled="disabled" 
                    style='background-color: #FFFFFF ' />
                    <td align="left"> ---Indisponível--- </td>
                <?php
                } 
                else { ?>
 
                    <input type="button" name="snovobotao" value=<?php print("$horaNovaFormatada");?> id="colunaEsquerda"
                       style='background-color: #00ff00' 
                        onclick=" <? session_start();
                        $_SESSION['sbotao'] = $horaNovaFormatada ?>;
                        fPegaDados('u_encaminhamento_exames.php','','none')"/></td>
                       <td align="left"> ----Disponível---- </td>
                       
                <?php } 
                   
?>
                
              </td>  
           </tr>
        </div>
      <?php  
 } ?> 
    </form>
  </div><!-- end #colunaEsquerda -->
</div>
</body>
</html>
 
Obs: Só tá levando via SESSION o conteúdo do último botão criado.