Replace this:
<div class="latest_ads">
<h1><strong><?php _e('Latest Listings', 'modern'); ?></strong></h1>
<?php if( osc_count_latest_items() == 0) { ?>
<p class="empty"><?php _e('No Latest Listings', 'modern'); ?></p>
<?php } else { ?>
<table border="0" cellspacing="0">
<tbody>
<?php $class = "even"; ?>
<?php while ( osc_has_latest_items() ) { ?>
<tr class="<?php echo $class. (osc_item_is_premium()?" premium":""); ?>">
<?php if( osc_images_enabled_at_items() ) { ?>
<td class="photo">
<?php if( osc_count_item_resources() ) { ?>
<a href="<?php echo osc_item_url(); ?>">
<img src="<?php echo osc_resource_thumbnail_url(); ?>" width="75" height="56" title="<?php echo osc_item_title(); ?>" alt="<?php echo osc_item_title(); ?>" />
</a>
<?php } else { ?>
<img src="<?php echo osc_current_web_theme_url('images/no_photo.gif'); ?>" alt="" title="" />
<?php } ?>
</td>
<?php } ?>
<td class="text">
<h3><a href="<?php echo osc_item_url(); ?>"><?php echo osc_item_title(); ?></a></h3>
<p><strong><?php if( osc_price_enabled_at_items() && osc_item_category_price_enabled() ) { echo osc_item_formated_price(); ?> - <?php } echo osc_item_city(); ?> (<?php echo osc_item_region();?>) - <?php echo osc_format_date(osc_item_pub_date()); ?></strong></p>
<p><?php echo osc_highlight( strip_tags( osc_item_description() ) ); ?></p>
</td>
</tr>
<?php $class = ($class == 'even') ? 'odd' : 'even'; ?>
<?php } ?>
</tbody>
</table>
<?php if( osc_count_latest_items() == osc_max_latest_items() ) { ?>
<p class='pagination'><?php echo osc_search_pagination(); ?></p>
<p class="see_more_link"><a href="<?php echo osc_search_show_all_url();?>"><strong><?php _e("See all offers", 'modern'); ?> »</strong></a></p>
<?php } ?>
<?php View::newInstance()->_erase('items'); } ?>
</div>
With this:
<div class="latest_ads">
<h1><strong><?php _e('Latest Listings', 'modern'); ?></strong></h1>
<?php if( osc_count_latest_items() == 0) { ?>
<p class="empty"><?php _e('No Latest Listings', 'modern'); ?></p>
<?php } else { ?>
<style type="text/css">
ul.grid_view{margin: 8px 0px 22px 0px;}
.grid_view li {display: inline; list-style: none; width: 160px; height: 210px; float: left; margin: 0px 4px 8px 4px; text-align: center; border: 1px solid #CCC; -webkit-border-radius: 3px; -moz-border-radius: 3px; border-radius: 3px; -webkit-box-shadow: 0 1px 2px rgba(0,0,0,.2); -moz-box-shadow: 0 1px 2px rgba(0,0,0,.2); box-shadow: 0 1px 2px rgba(0,0,0,.2); }
.grid_view li h3{ margin: 5px; max-height: 20px; overflow: hidden; text-overflow: ellipsis; background: #EEE; }
.grid_view li h3 a{ text-decoration: none; text-transform: uppercase;}
.grid_view li p{ max-height: 60px; overflow: hidden; text-overflow: ellipsis;}
.grid_view img{ border: 1px solid #EEE;}
</style>
<ul class="grid_view">
<?php while ( osc_has_latest_items() ) { ?>
<?php if( osc_images_enabled_at_items() ) { ?>
<li><h3><a href="<?php echo osc_item_url();?>"><?php echo osc_item_title();?></a></h3><?php if( osc_count_item_resources() ) { ?>
<a href="<?php echo osc_item_url();?>"><img src="<?php echo osc_resource_thumbnail_url() ; ?>" width="140px" height="110px" title="" alt="" /></a>
<?php } else { ?>
<a href="<?php echo osc_item_url();?>"><img src="<?php echo osc_current_web_theme_url('images/no_photo.gif') ; ?>" width="140px" height="110px" alt="" title=""/></a>
<?php } } ?>
<br/><p><?php if (osc_price_enabled_at_items()) { echo osc_item_formated_price(); }?><br /><strong><?php if (osc_item_city() != '') {echo osc_item_city();}if (osc_item_region() != '') {echo '(' . osc_item_region() . ')';}echo ' - ' . osc_format_date(osc_item_pub_date());?> </strong></p></li>
<?php } ?>
</ul>
<?php if( osc_count_latest_items() == osc_max_latest_items() ) { ?>
<p class='pagination'><?php echo osc_search_pagination(); ?></p>
<p class="see_more_link"><a href="<?php echo osc_search_show_all_url();?>"><strong><?php _e("See all offers", 'modern'); ?> »</strong></a></p>
<?php } ?>
<?php View::newInstance()->_erase('items'); } ?>
</div>
Is should give you grid view for Latest listings in Modern theme