tables.html

<!DOCTYPE html>
<html>
<head>
    <script type="text/javascript" src="jquery-1.8.2.min.js"></script>
    <script type="text/javascript">
        // page ready handler
        $(function() {
            // listen for click on the button
            $("#toTwoButton").bind("click", function(event) {
                // get all of the td elements inside of the table with an id = 'onecol'
                var origTds = $("#onecol td")

                // create a new table
                var newTable = $("<table>")

                // adjust origTds so that it has an even number of elements
                if ((origTds.size() % 2) != 0) {
                    origTds.push($("<td>"))
                }

                // loop through all of the original td elements and move them to the new table
                while (origTds.size() >0) {
                    // create a new row
                    var newRow = $("<tr>")
                    newTable.append(newRow)

                    // for each row (two td elements), add them to the newRow
                    $.each(origTds.splice(0, 2), function(index, item) {
                        newRow.append(item)
                    })
                }

                // add the table to the page
                $("body").prepend(newTable)

                // remove the old table
                $("#onecol").detach()

                // hide the button
                $("#toTwoButton").hide()
            })
        })
    </script>
    <style>
        table, td {
            border-style: solid;
            border-width: 1px;
        }
    </style>
</head>
<body>
    <table id="onecol">
        <tr>
            <td>One</td>
        </tr>
        <tr>
            <td>Two</td>
        </tr>
        <tr>
            <td>Three</td>
        </tr>
        <tr>
            <td>Four</td>
        </tr>
        <tr>
            <td>Five</td>
        </tr>
        <tr>
            <td>Six</td>
        </tr>
        <tr>
            <td>Seven</td>
        </tr>
    </table>
    <button id="toTwoButton">Utah, Gimme Two!</button>
</body>
</html>