HTML：

<table>
    <tr>
        <td>1</td>
        <td>4</td>
        <td>7</td>
    </tr>
    <tr>
        <td>2</td>
        <td>5</td>
        <td>8</td>
    </tr>
    <tr>
        <td>3</td>
        <td>6</td>
        <td>9</td>
    </tr>
</table>


<p><a href="#">Do it.</a></p>

js：

$("a").click(function(){
    $("table").each(function() {
        var $this = $(this);
        var newrows = [];
        $this.find("tr").each(function(){
            var i = 0;
            $(this).find("td").each(function(){
                i++;
                if(newrows[i] === undefined) { newrows[i] = $("<tr></tr>"); }
                newrows[i].append($(this));
            });
        });
        $this.find("tr").remove();
        $.each(newrows, function(){
            $this.append(this);
        });
    });

    return false;
});