<?php the_time('d F l') ?>
var supervise = {};
$('.date').each(function() { //Где '.date' - блок содержащий дату поста
var txt = $(this).text();
if (supervise[txt])
$(this).remove();
else
supervise[txt] = true;
});
Will only output the date if the current post’s date is different from the previous one output.
i.e. Only one date listing will show per day worth of posts shown in the loop, even if the function is called several times for each post.