A little placeholder jQuery snippet I've used for years now

jquery.placeholder.js

jQuery(function($) {
  var input              = document.createElement('input');
  var placeholderSupport = 'placeholder' in input;

  // prevent IE from leaking
  input = null;

  if (placeholderSupport) {
    return;
  }

  $('[placeholder]').focus(function() {
    var input = $(this);
    if (input.val() == input.attr('placeholder')) {
      input.val('').removeClass('placeholder');
    }
  }).blur(function() {
    var input = $(this);
    if (input.val() == '' || input.val() == input.attr('placeholder')) {
      input.addClass('placeholder').val(input.attr('placeholder'));
    }
  }).blur();

  $('[placeholder]').parents('form').submit(function() {
    $(this).find('[placeholder]').each(function() {
      var input = $(this);
      if (input.val() == input.attr('placeholder')) {
        input.val('');
      }
    })
  });
});