Jquery :: Keep Active Page Highlighted In Navigation Menu On Rollover

I'm building a WordPress site with a nice jQuery effect that fades/unfades images within a navigation menu on rollover. So when the mouse moves off the image, the colored image should fade back to reveal the original non-colored image. This works perfectly as-is, but client wants the active page to keep its colored/ highlighted menu image when mouse has moved off of it. The bolded line of the code is where I tried to set that up...

Code:
<?php wp_nav_menu( array( 'container_class' => 'menu-header', 'theme_location' => 'primary' ) ); ?>
<script type="text/javascript"><!-- this is from [URL]-->
// make nav images highlight on hover
// when the DOM is ready:
$(document).ready(function () {
// find the navigation elements and hook the hover event
$('#mainmenu li').hover(function() {
// on hovering over, find the element we want to fade *up*
var fade = $('> div', this);

// if the element is currently being animated (to a fadeOut)...
if (fade.is(':animated')) {
// ...take it's current opacity back up to 1
fade.stop().fadeTo(250, 1);
} else {
// fade in quickly
fade.fadeIn(250);
}}, function () {
// on hovering out, fade the element out
if (!is_page(current)){
var fade = $('> div', this);
if (fade.is(':animated')) {
fade.stop().fadeTo(3000, 0);
} else {
// fade away slowly
fade.fadeOut(2000);
}}});});
</script>

<ul id="mainmenu">
<li id="home">
<a href="/home"><img src="<?php bloginfo(url); ?>/wordpress/wp-content/uploads/2011/09/sara_inactive.png" alt="home" width="152" height="309" /></a>
<div>
<a href="/home"><img src="<?php bloginfo(url); ?>/wordpress/wp-content/uploads/2011/09/sara_active.png" alt="home" width="152" height="309" /></a>
</div>
</li>

WordPress should know whether the page is 'current' or not, so why doesn't this work? Currently the nav images remain highlighted when the mouse moves away. If I remove my attempt (the bolded line of code) then nav rollovers work beautifully, but active page still isn't represented with a colored nav menu image.