Im while using the next PHP to show numerous icons during my Wordpress theme:

// A sidebar for widgets, just because.
if ( is_active_sidebar( 'primary-widget-area' ) ) : ?>
        <?php dynamic_sidebar( 'primary-widget-area' ); ?>
<?php endif; ?>

Essentially each widget within the <ul> arrives as a listing item. I wish to have the ability to give a class towards the last list item within the list.

Is it feasible that i can do that with wordpress/php?

I remember when i coded that wordpress adds an initial and last classname to the foremost and last widget, you'll find the code in the ticket.

However per CSS you need to have the ability to address the final item using the [cde] CSS selector (all browsers although not IE 5.5 - IE 8). So most likely this already solves your problem.