After the update on a couple of installation I found that I lost my impagination: posts weren't showing up.
That was because I was using
$posts = z_get_posts_in_zone('example');
but this new 0.4 prepend 'zone' to the slug of the zone.
So I changed 'example' to 'zone-example' and it worked again.
I suggest that you write that on the changelog.
Thanks for your plugin,