New entries auto-loading when the scroll bar is around the bottom.

ajax_loader.css

#ajax_loader{
    position: fixed;
    //position: absolute;
    bottom: 20px;
    left: 50%;
    width: 140px;
    padding-top: 55px;
    padding-bottom: 10px;
    padding-left: 20px;
    padding-right: 20px;
    margin-left: -100px;
    background: black url("/images/ajax-loader.gif") no-repeat 50% 10px;
    opacity: .8;
    display: none;
    -moz-border-radius: 5px;
    -webkit-border-radius: 5px;
    border-radius: 5px;
    text-align: center;
    color: white;
    font-family: "Courier New", Courier, monospace;
    font-size: 12px;
}

autoload.js

$(document).ready(function(){
	var windowHeight, hitTest = 20, loaderEl, loadingStatus = false, page = 1;
	$(window).bind("resize", function(){
		windowHeight = $(document).height() - $(window).height();	
	});
	$(window).resize();
	$(window).scroll(function(){
		if(!loadingStatus){
			if(windowHeight-hitTest < $(window).scrollTop()){
				onPageScrolls();
				loadingStatus = true;
			}
		}
	});
	function onPageScrolls(){
		if($("#ajax_loader").length == 0){
			loaderEl = $("BODY").append("<div id='ajax_loader'>Загружается следующая страница</div>").find("#ajax_loader");
		}
	
		loaderEl.fadeIn("slow");
	
		$.ajax({
			url: "/ajax_posts",
			success: function(data){
				data = $.parseJSON(data);
				loaderEl.fadeOut("slow");
				if(data.page != data.last_page){
					loadingStatus = false;
				}
				$(".left").append(data.html);
				$(window).resize();
			}
		});
	}
});