var p = $.plot(...);

$.each(p.getData()[0].data, function(i, el){
  var o = p.pointOffset({x: el[0], y: el[1]});
  $('<div class="data-point-label">' + el[1] + '</div>').css( {
    position: 'absolute',
    left: o.left + 4,
    top: o.top - 43,
    display: 'none'
  }).appendTo(p.getPlaceholder()).fadeIn('slow');
});