Wp-admin is displaying what appears to be a limited-number of custom post types in the left-nav, as you can see in this screenshot: http://screencast.com/t/mlXhyJlMrXb
There are more custom post types than what are showing in that view.
These is no issue with these post types (that I'm aware of), and I've tested this by removing, say, Articles (a custom post type from screenshot above) from the list of registered post types in functions.php, and one of the missing post types reappears.
Which makes me think it's solely a display issue - i.e. WordPress will only display a limited number of custom post types.
Any ideas how to display all of my custom post types?