This is what I've done

gistfile1.erb

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function(){
    var micropostIds = [<%= @microposts.map {|micropost| micropost.id }.join(',') %>];
    $.each(micropostIds, function (index, value) {
        $(".slidingDiv" + value).hide();
        $(".show_hide" + value).show().click(function () {
            $(".slidingDiv" + value).slideToggle();
        });
    });
});
</script>
<% for micropost in @microposts %>
<%= link_to image_tag('Comment.png', :mouseover => "Comment-Over.png", :class => "show_hide"),  "#" %>
<div class="slidingDiv<%= micropost.id %>">
	<%= render  :partial => 'microposts/display', :locals => { :micropost => @micropost } %>
</div>  
<a href="#" class="show_hide<%= micropost.id %>">hide</a>

<% end %>