Extracting Javascript functions
Add the refresh-rates map to #refresh-buttons element ( use .data() function ), optimize amount of $() calls:

$(document).ready(function() {
    var refresh_btns$;

    // you can store id map where ever you prefer to
    // I've figured it would be good to keep them with
    // the element they are related to
    ( refresh_btns$ = $("#refresh-buttons") )
    .data(
        "refreshRates",
        {
            "refresh-off"    :50000000,
            "refresh-5-sec"  :5000,
            "refresh-30-sec" :30000,
            "refresh-60-sec" :60000
        }
    )
    .on("click", "button", function () {
        var
        interval = refresh_btns$.data("refreshRates")[ this.id ] || 0;
        if (
            interval !== 0
        ) {
            // yeah m_x is right about .toggleClass()
            // it producess weird behaviour
            // this shold to the job
            $( this )
            .addClass("pressed-button")
            .siblings()
            .removeClass("pressed-button");

            clearInterval(intervalId);
            intervalId =
            setInterval(
                function () {
                    $('#status-tables')
                    .load(
                        '/dashboard/index #status-tables',
                        function () {
                            $("#workstation-table").tablesorter();
                            $("#report-table1, #report-table2")
                            .tablesorter( { sortList : [ [ 1, 0 ] ] } );
                        }
                    );
                },
                interval
            );
        }
    });
});