Easy using WP query (get to know it…)
<ul>
<?php
$recentPosts = new WP_Query();
$recentPosts->query('showposts=2'); // SET AMOUNT HERE
?>
<?php while ($recentPosts->have_posts()) : $recentPosts->the_post(); ?>
<li><div class="slide"><?php the_content(); ?></div></li>
<?php endwhile; ?>
</ul>
Hope this helps. Let me know if you encounter any issuse.
EDIT 1:
* explenation – just added a small conditional counter
<ul>
<?php
$count = 1;
while(has_posts()): the_post();
?>
<?php if ($count == 1) {echo '<li><div class="slide">';} ?>
<?php the_content(); ?>
<?php if ($count == 3) {echo '</div></li>'; $count = 1;} else {$count++;} ?>
<?php endwhile; ?>
</ul>
EDIT 2:
* please note i changed has_post to have_post (think it should be that way? your call)
<?php
echo '<ul>';
$count = 1;
while(have_posts()): the_post();
if ($count == 1) {$slideOpenTag = '<li><div class="slide">';} else {$slideOpenTag = '';}
if ($slideOpenTag) {echo $slideOpenTag;}
the_content();
if ($count == 3) {$slideCloseTag = '</div></li>'; $count = 1;} else {$count++; $slideCloseTag = '';}
if ($slideCloseTag) {echo $slideCloseTag;}
endwhile;
if (!$slideCloseTag) {echo '</div></li>';}
echo '<ul>';
?>