Trouble getting 'edit_posts' capabilities to take effect

I created a new role that includes ‘edit_post’ capability; however, anyone assigned to this role does not show-up in the AUTHORS meta-box as someone to whom the Post can be attributed.

My new role actually supports edit_post, edit_published_posts, delet_posts, delete_published_posts, publish_posts, read_posts in addition to a couple of custom capabilities.

This was strange, so i wrote a quick little loop to show me all of the blog members who have ‘edit_post’ capability. The only ones that it would reported with that capability were Administrators.

Of course, changing a user to have a built-in role (e.g. Editor or Author) and, magically, they’re reported as having the capability.

Is there some mystical incantation that I’m supposed to embark before capabilities are “active”?

(BTW, I’m using WP 3.1. To make sure I’m seeing/assigning capabilities correctly, I used Tadlock’s MEMBERS plug-in then double-checked it again using Garagulya’s User Role Editor plug-in