If you are using superfish menus in views/layout.html hee is what I did.
I changed
<script type="text/javascript">
jQuery(document).ready(function(){
jQuery('ul.sf-menu').superfish();});
</script>
to be
<script type="text/javascript">
jQuery(document).ready(function(){
jQuery('ul.sf-menu').superfish({pathClass:
'web2py-menu-active'});});
</script>
Really only a parameter addition in third line, extra lines are there to add
context.
Then look for the superfish.css file for the selector
.sf-menu a:focus, .sf-menu a:hover, .sf-menu a:active {
if you want a different color than the default.
Ron