WooCommerce 2.0.4 - Change number of columns of thumbnails for Up Sells on product page.

gistfile1.php

<?php

// first remove the action defined in woocommerce-hooks.php
remove_action( 'woocommerce_after_single_product_summary', 'woocommerce_upsell_display', 15 );

// modeled off of the woocommerce_upsell_display() function in woocommerce-template.php
// change $columns to desired number of columns
  function my_woocommerce_upsell_display( $posts_per_page = '-1', $columns = 5, $orderby = 'rand' ) {
		woocommerce_get_template( 'single-product/up-sells.php', array(
				'posts_per_page'  => $posts_per_page,
				'orderby'    => $orderby,
				'columns'    => $columns
			) );
	}
// re-add the action for display
add_action( 'woocommerce_after_single_product_summary', 'my_woocommerce_upsell_display', 15 );