function hoverInit() {
	$$('img').each(function(img) {
		if (img.hasClass('hover')) {
			var imgSrc = img.src;
			var lastDotPos = imgSrc.lastIndexOf(".");
			var imgName = imgSrc.substring(0, lastDotPos);
			var imgExt = imgSrc.substring(lastDotPos + 1);
			var overSrc = imgName + "_o." + imgExt;
			var overImg = new Image(); overImg.src = overSrc;
			img.addEvent('mouseover', hoverSwap.bindAsEventListener(img, overSrc));
			img.addEvent('mouseout', hoverSwap.bindAsEventListener(img, imgSrc));
		}
	});
}

function hoverSwap(evt, src) {
	if (this.src != src)
		this.src = src;
}

window.addEvent('domready', hoverInit);