Sorting thumbnails by category

Can anyone help? Please ?? I simply want to sort my thumbnails dynamically by category. Also, I would like to list the title of the category above each group of thumbnails.

This is my code so far
<!-- put the stuff that make the thumbnails here -->
<?php
$posts = get_posts('numberposts=50&offset=1&category=1');
foreach($posts as $post) :
setup_postdata($post);

?>

<!-- BEGIN post -->
<div id="postg-<?php the_ID(); ?>" class="postg clearfix">

<a>" title="">

<!-- install for yapb thumbails -->
<?php if (!is_null($image = YapbImage::getInstanceFromDb($post->ID))): ?>
<div id="thumbs">

<ul><p><img src="<?php echo $image->getThumbnailHref(array('w=150', 'h=66','zc=1','fltr[]=usm|40|0.5|3')) ?>" width="150" height="66" ></p></ul>
</div>
<?php endif ?>
<!-- install for yapb thumbails -->

</a>

</div>
<!-- END post -->
<?php endforeach; ?>
<!-- put the stuff that make the thumbnails here -->

Bumping after one hour is a good way to remove yourself from the “unanswered posts” queue that many volunteers start with.

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