Rollover marker popups for leaflet

HTML

<script src="http://cdn.leafletjs.com/leaflet-0.5.1/leaflet.js"></script>
<link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.5.1/leaflet.css">
<div id="map"></div>

CSS

html, body, #map {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
}

JavaScript

var cloudmade = L.tileLayer('http://{s}.tile.cloudmade.com/{key}/997/256/{z}/{x}/{y}.png', {
    maxZoom: 18,
    attribution: 'Map data &copy; 2011 OpenStreetMap contributors, Imagery &copy; 2011 CloudMade',
    key: 'BC9A493B41014CAABB98F0471D759707'
});

var map = L.map('map')
    .setView([51.75, 0], 9)
    .addLayer(cloudmade);

var marker1 = new L.marker([51.5, -0.09]);
var marker2 = new L.marker([52, -0]);

var markers = L.layerGroup([marker1, marker2]);
map.addLayer(markers);

map.removeLayer(markers);