So today I got interested in trackbacks and comments. And low and behold, I discovered that you couldn't enter them anywhere, or find the trackback uri! much fiddling later, I discovered the reason for this somewhat accidentally, clued in by a comment at http://wordpress.org/support/topic/38459 (asking if the user there had edited the permalink structure). Apparently my permalink structure choice was subtly unacceptable, resulting in the posts showing but without the extra html displaying comments and trackbacks and allowing you to find the trackback uri and post comments (if you are registered and logged in). So adding a /%post_id% to the permalink structure (which rather defeats the purpose of permalinks, doesn't it?) solves that, and it now displays correctly.
