Testing WP Gears and the Heartbeat API, WP Gears is at https://github.com/10up/WP-Gears (NOTE: this plugin is run continuously, triggered by 'plugins_loaded', you should use an event triggered by the user (onclick, onhover etc))

wp-gears-heartbeat.php

<?php
/*
Plugin Name: WP Gears & Heartbeat
Version: 0.0.6
Description: Testing WP Gears and the Heartbeat API
Author: Per Soderlind
Author URI: https://soderlind.no
Plugin URI: https://gist.github.com/soderlind/94629e4ae933407d823c
License: GPL
*/
// Exit if accessed directly
if ( ! defined( 'ABSPATH' ) ) { 
	exit;
}
/*
 *  WP Gears
 */
// Exit if WP Gears isn't installed (WP Gears is at https://github.com/10up/WP-Gears)
if ( ! function_exists( 'wp_async_task_add' ) ) { 
	exit;
}

function add_wp_gears_async_task() {
	wp_async_task_add( 'wp_gears_heartbeat_worker', array( 'action' => 'gettime' ), 'high' );
}
/*
 * NOTE, this plugin was written to test if I could use WP Gears with the Heartbeat API and not 
 *       bothering to write a UI I used plugins_load.
 *       You should call wp_async_task_add using an user triggerd action like a button click.
 */
add_action( 'plugins_loaded', 'add_wp_gears_async_task' );

if ( ! class_exists( 'WP_Gears_Get_Time_Worker' ) ) {
	class WP_Gears_Get_Time_Worker {
		static function wp_gears_heartbeat_worker_callback( $args ) {
			//if ( 'gettime' == $args['action']) { // doesn't work, $args is a string with value = 'gettime'
			sleep( 1 ); // without, you'll  get ,in supervisor, "INFO gave up: nn_worker-00 entered FATAL state, too many start retries too quickly"
			update_option( 'wp-gears-heartbeat-time_' . $_GET['doing_wp_cron'],   time() ); // $_GET['doing_wp_cron'] is unique
			//}
		}
	}
}
add_action( 'wp_gears_heartbeat_worker', array( 'WP_Gears_Get_Time_Worker', 'wp_gears_heartbeat_worker_callback' ) );

/*
 * Heartbeat
 */
function wp_gears_heartbeat_init() {
	//add_filter( 'heartbeat_nopriv_received', 'wp_gears_heartbeat', 10, 3 );
	add_filter( 'heartbeat_received', 'wp_gears_heartbeat', 10, 2 );
	add_action( 'admin_enqueue_scripts', 'wp_gears_heartbeat_script_enqueue' );
}
add_action( 'plugins_loaded', 'wp_gears_heartbeat_init' );

function wp_gears_heartbeat( $response, $data ) {

	// Get all options since last heartbeat
	$all_options = wp_load_alloptions(); // will this cause a heavy load?
	$my_options = array();
	// Find my options
	foreach ( $all_options as $name => $value ) {
		if ( stristr( $name, 'wp-gears-heartbeat-time_' ) ) {
			$my_options[] = $value;
			delete_option( $name );
		}
	}
	if ( count( $my_options ) ) {
		$response['wp-gears-heartbeat-time'] = json_encode( $my_options );
	}
	// If the above conditions aren't met, we still pass along the existing $response.
	return $response;
}

function wp_gears_heartbeat_script_enqueue( $hook_suffix ) {
	// Make sure the JS part of the Heartbeat API is loaded.
	wp_enqueue_script( 'heartbeat' );
	// Output the JavaScript we need.
	add_action( 'admin_print_footer_scripts', 'wp_gears_heartbeat_js', 20 );
}

function wp_gears_heartbeat_js() {
?>
	<script>
	(function($){
		// Hook into the heartbeat-send
		$(document).on( 'heartbeat-send.wp-gears-heartbeat-time', function( e, data ) {
			data['wp-gears-heartbeat-time'] = 'bootstrap heartbeat';
			window.wp.heartbeat.interval( 15 );
		});
		// Listen for the tick custom event.
		$(document).on( 'heartbeat-tick.wp-gears-heartbeat-time', function( e, data ) {
			// Double-check we have the data we're listening for
			if ( ! data['wp-gears-heartbeat-time'] ) {
				return;
			}
			console.group('Gearman:');
			var jsonObj = $.parseJSON( data['wp-gears-heartbeat-time'] );
			$.each( jsonObj, function( k, v ) {
				//convert the epoch time to a readable format
				var time_from_gearman = new Date( v * 1000 );
				console.log( time_from_gearman.toLocaleString() );
			});
			console.groupEnd();
		});

		// Initial connection to cement our new interval timing
		window.wp.heartbeat.connectNow();
	}(jQuery));
	</script>
	<?php
}

I'm testing WP Gears together with the Heartbeat API. The idea is that heartbeat should update status when a gearman job is done.

I had a race condition, it is fixed now: 10up/WP-Minions#5 (comment)