You can have something like this:
$('#xdiv').html($('#xdiv').data('placeholder'));
$('#xdiv').keydown(function() {
if ($(this).html() == $(this).data('placeholder')) {
$('#xdiv').html('');
}
})
$('#xdiv').keyup(function() {
if ($(this).html() == '') {
$('#xdiv').html($('#xdiv').data('placeholder'));
}
})
Initially it sets DIV's HTML to placeholder text. Then when user begins to type (on keydown) it checks if DIV still has the placeholder text and if so - removes it. And since user can delete all the data - it checks (on keyup) if DIV is empty, and if so - restores placeholder's text.