Not sure if it'll help anyone but I did end up using AJAX (similar to what crhayes said above).

The AJAX function that will be called looks like this:

public function getLoginStatus()
{
    return Response::json( array( 'status' => Sentry::check() ) );
}
/* getLoginStatus */

The jQuery initialisation looks like this:

jQuery.fn.timer = function()
{
    $.get( "/ajax/login-status", function( data )
    {
        data.status == false ? $( 'li#status').show() : $( 'li#status').hide();
    });
}

Bind the timer to the relevant page element like this:

window.setInterval(function()
{
    $( "li#status" ).timer();
}, 1000);