woothemes/woocommerce — pull request #1555 by markmarijnissen (2012-10-02 12:42:15+00:00)
Title: Check cross-sells before displaying related products in single product template

Related products are similar to cross-sells.

If the user defines cross-sells, they should replace default related products.

If you disagree (and find "related products" and "cross-sells" fundamentally different, and think both need to be displayed), then I suggest adding a 'cross-sells.php' template, in similar fashion as 'up-sells.php'